UFOs in the Catholic Church

This article includes excerpts and/or summaries from Daniel O'Connor's monumental book "Only Man Bears his Image" (Used with permission)

The UFO question touches on the very essence of the creature’s relationship with its Creator.

  • What happens to the biblical narrative of God's monogamous marriage to his human Church. Does he have a harem of wives? Would he use this narrative in the Bible knowing we'd "discover" that he had other wives?
  • Is man the unique being of all material creation made in the Divine Image, or only one of multiple (even innumerable!) races of rational creatures throughout the universe?
  • Does the human race have siblings, or not? (If any intelligent incarnate creatures exist anywhere in the cosmos, they too would be our brethren.)
  • Have we been failing, for 2,000 years, to pray for the vast majority of those in dire need of our prayers?
  • Is Jesus Christ truly the only Incarnation of the Second Person of the Eternal Trinity, or is He just one of a whole population of Divine Individuals that are each God-Incarnate?
  • Is the Blessed Virgin the Mother of God, or just one of countless such Immaculate Mothers?
  • Is the Bible so fundamentally lacking in its ability to provide us a coherent worldview that it could entirely leave out any acknowledgement whatsoever of the vast majority of God’s eternally oriented (i.e., rational) creation?
  • Is the human body—assumed by God Himself 2,000 years ago—merely one more-or-less arbitrary way of designing an incarnate intelligent being just as a Volkswagen Beetle is one way of configuring a motor vehicle?
  • Or, rather, is Scripture correct when it teaches that “God made man right,” (Ecclesiastes 7:29),
  • And, of supreme and likely imminent importance: if some manner of “alien contact” is presented on the news tomorrow, should we take what these “aliens” claim at face value and engage in dialogue with them, hoping to learn from their teachings as we do from other human societies? Or, should we switch into discernment mode in order to better understand the darker reality of what we may well truly be dealing with? (Hint: the latter.)

Many of the most pervasive diabolical deceptions the Church has already refuted arose from false prophets who have proposed to present to the Faithful the hitherto “missing Chapters” of Salvation History: Gnosticism, Islam, Mormonism, Seventh Day Adventism, various New Age “revelations,” and too many others to list.

So when we see ET promoters make similar claims we should take note.

Like many churches these days, there is a war in the Catholic Church between adherants to the biblical account of the world and the adherents to the narrative of the psuedo-scientific community.

Extra-terrestrial (ET) promoters love to assert that there is no official Catholic position offered by the Magisterium or the traditions of the Catholic Church so they can freely promote ET belief within the Church.

The Catholic Church is bound by several principles:

  1. The Bible
  2. The Early Church Father's interpretation of the Bible
  3. Magisterial pronouncements
  4. The sensus fidelium, when a belief is universally held by the faithful (Pope, cardinals, bishops, priests and laity).

“It is not possible for there to be another earth than this one.”

—St. Thomas Aquinas

“There is another heresy that says that there are infinite and innumerable worlds, according to the empty opinion of certain philosophers—since Scripture has said that there is one world...”[1]
St. Philastrius, Bishop of Brescia (†397 A.D.)

The Catholic Church has long been aware that Christianity has been the only religion not to believe in aliens. Hinduism, Buddhism, Islam and a multitude of pagan religions have always held that there are multiple civilizations on other planets.

Nevertheless, the Catholic Church has consistently rejected the idea of aliens in the heirarchy of reality.

“Man occupies a unique place in creation: (I) he is ‘in the image of God’; (II) in his own nature he unites the spiritual and material worlds; (III) he is created ‘male and female’; (IV) God established him in his friendship.” —Catechism of the Catholic Church, §355

Creation is used in the Catechism to mean the creation of everything, including the universe.

289 Among all the Scriptural texts about creation, the first three chapters of Genesis occupy a unique place. 

The book of Genesis says:

In the beginning God created the heavens and the earth. (Gen 1.1)

And God said, “Let there be lights in the vault of the sky to separate the day from the night, and let them serve as signs to mark sacred times, and days and years, 15 and let them be lights in the vault of the sky to give light on the earth.” And it was so. 16 God made two great lights—the greater light to govern the day and the lesser light to govern the night. He also made the stars. 17 God set them in the vault of the sky to give light on the earth, 18 to govern the day and the night, and to separate light from darkness. (Gen 1:14)

The Nicene Creed

In this Creed, Christians profess the following:

...I believe in one Lord Jesus Christ, the Only Begotten Son of God ... begotten, not made, consubstantial with the Father; through him all things were made. For us men and for our salvation he came down from heaven... (The Nicene Creed)

  • Jesus Christ, is literally consubstantial with the almighty Father who made the entire universe, not merely similar or related; rather, Jesus and the Father are one in their very being.
  • [Jesus] is the radiance of [God’s] glory and the exact representation of His nature... (Hebrews 1:3. NASB)

  • This Creed repudiates any cryptic interpretations of Jesus’ nature or mission which would regard Him as somehow “less” than God; somehow a mere “manifestation” of God; somehow on par with “other Sons of God.” If any other incarnation existed, it too would be “Lord;” it too would be a “Begotten Son” of God.
  • Jesus is the only "one", Lord; the “only” Begotten Son of God; the one “through [whom] all things were made.
  • Jesus came down “for us men and for our salvation.”
  • Not only, therefore, does the Nicene Creed rule out the possibility of multiple incarnations. It also rules out the possibility that the Incarnation transpired for the sake of alien races.

All of Creation doens't include aliens

This classic painting from the 16th century depicts the full scpectrum of reality from hell up to heaven and everything in between. There are no gaps, no space for an "unknown alien" or life on other planets. his also shows the hierarchy of conciousness (of being) with humans right below angels and no gap for aliens that are more advanced than us.

The Great Chain of Being

The Great Chain of Being from  Didacus Valades

This image represents the universal belief of the Church, sensus fidelium.

In our timeline of alien belief we see universal condemnation of UFO's in Christianity before the "enlightenment".

The 1800's were heavily dominated by the influence of freemasonry and the occult. The New Age has its roots in the Theosophy movement founded by Helen Blavasky. Ouija, Theosophy, séances, automatic writing, mediums, secret societies, table-rapping, spirit-photography, mesmerism, telepathy, divination, etc.—all of which are simply portals for demons—were everywhere. Extraterrestrial fixation was just another item to add on to that list.

This was before powerful telescopes and there was near universal belief that all the other planets in our solar system were inhabited by aliens. This infected many Catholics and the Pope responded.

[it is condemned to hold the positions that:]

“Divine revelation is imperfect, and therefore subject to a continual and indefinite progress, corresponding with the advancement of human reason.” (§5)

The method and principles by which the old scholastic doctors cultivated theology are no longer suitable to the demands of our times and to the progress of the sciences.” (§13)

“The obligation by which Catholic teachers and authors are strictly bound is confined to those things only which are proposed to universal belief as dogmas of faith by the infallible judgment of the Church.” (§22)

The Pope concluded his condemnation of these errors with a grave warning:

... how sad and full of perils is the condition of Catholics in the regions of Europe which We have mentioned. Nor are things any better or circumstances calmer in America...

Many of the writings, even of Catholics of the time were full of alien discussion. In the early 1900's as telescopes improved, each assertion by ET promoters of the 1800's collapsed one by one and achedemia swung back to a position of not believing in aliens.

This was the status quo for 40 years until 1947, when the devil had to implement a new strategy. A crashed weather ballon began the modern UFO age.

Uniqueness of man

The [human] body, in fact, and only the [human] body, is capable of making visible what is invisible: the spiritual and the divine. It has been created to transfer into the visible reality of the world, the mystery hidden from eternity in God, and thus to be a sign of it (Theology of the Body, 19:4)
- Saint Pope St. John Paul II

“Human beings were created in the image and likeness of God, and so in the image and likeness of the Son, for he is the perfect image of his Father. To be made in the image and likeness of the Son not only means that human beings possess intelligence – the ability to know the truth and to will and love what is good—but also that our bodies must ... bear the image of God. For it is tedehe whole of us as human beings that bears God’s image.”
—Fr. Thomas Weinandy [5]

“Man is the perfection of the universe...” —St. Francis de Sales. Treatise on the Love of God. Book X. Chapter 1.

The Scriptural expression “heaven and earth” means all that exists, creation in its entirety. ... “the earth” is the world of men, while “heaven” or “the heavens” can designate both the firmament and God’s own “place”—”our Father in heaven” and consequently the “heaven” too which is eschatological glory. Finally, “heaven” refers to the saints and the “place” of the spiritual creatures, the angels, who surround God.”

—Catechism of the Catholic Church, §326

Popes can bind Heaven, what about popes on other planets?

Jesus said to human popes, "Whatever you bind in Heaven is bound”,(Mat 16:18-19). There is only one Heaven, which is bound by 266 men on earth, successors of Peter, who need not consult with any aliens to ensure their ex-cathedra declarations remain consistent with similar declarations of extraterrestrial popes.

Scripture’s Creation Account Rules Out Aliens

We have a separate article on UFO's in the Bible

Did any popes speak in favour of ETs?

There is a JPII comment on ETs purported by Dr. Thigpen, an ET advocate, who claims Monsignor Corrado Balducci, another ET promoter, says JPII responded to a kid about UFOs during a trip. There is no evidence of this. Transcripts on the Vatican site of this papal visit have no mention of aliens. In the 27 year pontificate of JPII and 8 years of BXVI, this unverifiable 2nd hand hearsay is all that ET promoters can come up with for papal endorsements of aliens from these fathers of the Catechism.

Show baseless claim There was one claim that was an unverifiable 2nd hand hearsay. Dr. Thigpen, an ET advocate, claims Monsignor Corrado Balducci, another ET promoter, says JPII responded to a kid about UFOs during a trip. There is no evidence of this. Transcripts on the Vatican site of this papal visit have no mention of aliens.

What about Pope Francis?

Show Pope Francis comments 

Indeed, for them it was unthinkable even to enter a house and sit at table with uncircumcised men, for reasons of impurity. Yet Peter not only did this but he even baptized them. In short, the Pope said, they thought he was was [sic] a “madman”. Just as if, for example, tomorrow an expedition of Martians came, green, with long noses and big ears, just like children draw them ... and one were to say, ‘I want to be baptized!’. What would happen?[425]

While this is another example of an imprudent Francis comment, Time Magazine printed a correction to their origianl sensationalist headline the following day "“Pope Francis was using Martians to illustrate that the church must be open to whatever, or whoever, may seem socially foreign and unaccepted.”

Two years later, in an interview, Francis was asked about his views on the existence of other beings in the universe (i.e., aliens), and responded “Honestly I wouldn’t know how to answer.”

Further Pope Francis has made clear his opinion.

On June 19th, 2023, the 400th anniversary of the birth of Blaise Pascal, Pope Francis promulgated Sublimitas et Miseria Hominis

... Human reason is a marvel of creation, which sets man apart from all other creatures....

Highest ranking ET promoter

Even the secular Wikipedia says:

Monsignor Corrado Balducci (the highest ranking Catholic ET promoter) invited the Catholic Church to reconsider its position on this issue (ETs). (source)

This demonstrates that:

  1. Its common knowledge that the Church does have a position against ETs
  2. Balducci was the highest ranking ET advocate around the Vatican, not the Pope

Personal opions of Popes

Moreover, even if a hypothetical pope did believe in aliens, the words of Magisterial documents must speak for themselves regardless of the intention of the Pope. For instance, the infamous footnote of Amoris Laetetia can be read with a hermeneutic of continuity even though Pope Francis' intented to break tradition. The Holy Spirit protects magisterial documents from imperfect popes. This is the gift of infallibility. However, in the case of UFOs, this protection is not necessary because the popes never advocated for UFOs.

The Vatican lumps UFO belief with the New Age

In its groundbreaking report on the New Age the Vatican says:

... in the more popular forms of New Age, “individuals and groups are living out their own fantasies of adventure and power, usually of an occult or millenarian form.... The principal characteristic of this level is attachment to a private world of ego-fulfilment and a consequent (though not always apparent) withdrawal from the world. On this level, the New Age has become populated with strange and exotic beings, masters, adepts, extraterrestrials; it is a place of psychic powers and occult mysteries, of conspiracies and hidden teachings”. (source)

Catechism rules out aliens

“Of all visible creatures, only man is able to know and love his creator...”
Cat §356

Some ET promoters try to limit the passage to creatures on Earth. However, the Catechism explicitly refers to the universe as its context, and it puts man in this context.

The universe, created in and by the eternal Word, the "image of the invisible God", is destined for and addressed to man, himself created in the "image of God" and called to a personal relationship with God. §299

Show 14 more references to the universe in the Catechism

...knowledge of God as the origin and the end of the universe. §32

It is not only a question of knowing when and how the universe arose physically, or when man appeared, but rather of discovering the meaning of such an origin: is the universe governed by chance, blind fate, anonymous necessity, or by a transcendent, intelligent and good Being called "God"? §284

The universe was created "in a state of journeying" (in statu viae) toward an ultimate perfection yet to be attained, to which God has destined it.  §302

God alone created the universe, freely, directly and without any help. §317

... when Christ, lying in the tomb, reveals God's great sabbath rest after the fulfillment of man's salvation, which brings peace to the whole universe. §624

"The eternal Father, in accordance with the utterly gratuitous and mysterious design of his wisdom and goodness, created the whole universe and chose to raise up men to share in his own divine life," §759

Christ, King and Lord of the universe §786

... There is one Father of the universe, one Logos of the universe, and also one Holy Spirit, everywhere one and the same; there is also one virgin become mother, and I should like to call her "Church." §813

The King of the universe §992

The visible universe, then, is itself destined to be transformed, "so that the world itself, restored to its original state, facing no further obstacles, should be at the service of the just," sharing their glorification in the risen Jesus Christ. §1047

...the material universe itself will be transformed ... §1060

Life extends over all beings and fills them with unlimited light; the Orient of orients pervades the universe, and he who was "before the daystar" and before the heavenly bodies, immortal and vast, the great Christ, shines over all beings more brightly than the sun. §1165

The dominion granted by the Creator over the mineral, vegetable, and animal resources of the universe cannot be separated from respect for moral obligations, including those toward generations to come. §2456

He takes them and offers praise and glory to the Father of the universe §1345

Some have postulated that rational beings on any planet are "men", but that is ruled out by the infallible dogma that all men are descendants of Adam and Eve. (Papal Encyclical Humani Generis, para. 26)

In a letter to St. Boniface, Pope St. Zachary wrote the following about a certain cleric named Virgil:

As for his perverse and abominable teaching, which he has proclaimed in opposition to God, and to his own soul’s detriment... that there are another world and other men beneath the earth, or even the sun and moon...take counsel and then expel him from the church, stripped of his priestly dignity.

Pope Pius II said

... most pernicious errors...a sacrilegious attempt against the dogmas of the holy Fathers” taught by a certain Zaninus de Solcia. Among these “sacrilegious” errors were the following condemned propositions ... (3) God created another world than this one, and in its time many other men and women existed, and consequently Adam was not the first man...

“Cum sicut accepimus,” November 14, 1459
Only Man Bears His Image: (p. 202)

For those who think this Magisterial statement does not apply to the current age, Daniel O'Connor has an apologetic here.

Belief in Aliens is not compatible with Catholic Eschatology, which has Christ coming back at the end of the universe and the end of all time.

Show 14 more references to the universe in the Catechism

“...the first historical coming of Christ ... invites us to look forward with expectation to his second coming at the end of time.”[19] (Pope John Paul II.)

“God does not will to grant to the just the full effect of the victory over death until the end of time has come...” (Pope Pius XII. Munificentissimus Deus. §4,5)

“At the end of time [the Church] will gloriously achieve completion, when, as is read in the Fathers, all the just, from Adam ... will be gathered together with the Father in the universal Church ... at the end of time, when Christ, our life, shall appear...” (Lumen Gentium. §2,9)

“...apostolic preaching, which is expressed in a special way in the inspired books, was to be preserved by an unending succession of preachers until the end of time.” (Dei Verbum. §8)

“[The Mass] will continue to be offered without interruption till the end of time” (Pope Pius XI. Ad Catholici Sacerdotii. §14)

“...the Church grows with spiritual increase throughout the world down to the end of time.” (Pope John XXIII. Sacerdotii Nostri Primordia. §53)

“Within the dimension of time the world was created ... its goal [is] in the glorious return of the Son of God at the end of time.” (Pope John Paul II. Dies Domini. §74)

“Certainly Christ is a King for ever; and though invisible, He continues unto the end of time to govern and guard His church from Heaven” (Pope Leo XIII. Satis Cognitum. §11)

“[God,] in the times of Noah brought the deluge because of man’s disobedience ... [and] will bring [His justice] on the day of judgment at the end of time” (St. Irenaeus. Against Heresies. Book IV. Chapter 36. §4)

“He has determined at the end of time to pass judgment on the living and the dead ... He defers it, however, until the end of time, when He will pour forth His wrath in power and heavenly might.” (Lactantius. The Divine Institutes. Book Two. Chapter 17.)

“Sanctify this offering in your mercy, so that they who by your gift have today united themselves more closely to your son may hasten gladly to meet him when he comes in glory at the end of time.” (Roman Missal. Mass for the Consecration of Virgins. Eucharistic Prayer I. Hanc Igitur.)

“[In] Advent ... [our] minds and hearts are led to look forward to Christ’s Second Coming at the end of time.” (Roman Missal. Universal Norms. V. §39)

“When the resurrection occurs, it will not be time but the end of time.” (St. Thomas Aquinas. Summa Theologica. Supplement. Question 77. Article 3.)

“When [Christ] comes at the end of time to judge the living and the dead...” (Catechism of the Catholic Church, §682)

The compenium of social doctrine reinforces the Catechism

Some ET promoters have suggested that the Catechism be updated to allow for aliens. This demonstrates that they are aware that it disallows alien belief. But its not only the Catechism they would need to change. The Compendium of the Social Doctrine of the Church points out, in respect to its own content, that it:

...has the same dignity and authority as her moral teaching. It is authentic Magisterium, which obligates the faithful to adhere to it.” (§80)

Within this Compendium, we are taught that:

Only man and woman, among all creatures, were made by God ‘in his own image’ (Gen 1:27). The Lord entrusted all of creation to their responsibility... (§451)

So ET promoters would have to comb through the Magisterial documents and change more than the Catechism to accommodate their belief.

The "soul" of the Church is the Holy Spirit

Catechism 813

The Church is one because of her "soul": "It is the Holy Spirit, dwelling in those who believe and pervading and ruling over the entire Church, who brings about that wonderful communion of the faithful and joins them together so intimately in Christ that he is the principle of the Church's unity." Unity is of the essence of the Church: 

What an astonishing mystery! There is one Father of the universe, one Logos of the universe, and also one Holy Spirit, everywhere one and the same; there is also one virgin become mother, and I should like to call her "Church." - Catechism quoting St. Clement of Alexandria

This is why Pope Leo XIII taught, in his encyclical Divinum illud munus: Let it suffice to state that, as Christ is the Head of the Church, so is the Holy Ghost her soul.

“What the soul is in our body, that is the Holy Ghost in Christ’s body, the Church” [St. Augustine. Sermon 187]. This being so, no further and fuller “manifestation and revelation of the Divine Spirit” may be imagined or expected; for that which now takes place in the Church is the most perfect possible, and

The Holy Spirit would not ensoul hundreds of Churches on different planets and provide his Church on earth a unique relationship. Especially, knowing that there would be a "day of disclosure" near the time of the antichrist.

God the Father would need to tell his children about their siblings

Siblings have an inalienable right to know of each other. This is a simple demand of justice of which even the secular are well aware.

Yet the Bible and the Magisterium make no mention of aliens, and rule them out. This would mean God would be hiding our siblings from us. A good father would never do that.

The Sensus Fidelium

“The absurdity of absurdities and the most horrible unreason of all is this: that while holding that the whole Church may have erred for a thousand years in the understanding of the Word of God, Luther, Zwingli, Calvin can guarantee that they understand it aright.” —St. Francis de Sales, Doctor of the Church. The Catholic Controversy (Part 2, Art. 8, Ch. 1)

The Catechism of the Catholic Church teaches:

The whole body of the faithful ... cannot err in matters of belief. This characteristic is shown in the supernatural appreciation of faith (sensus fidei) on the part of the whole people, when...they manifest a universal consent in matters of faith and morals. (§92. Quoting Vatican II’s Lumen Gentium)

There has never been a dogmatic statement, or Scriptural passage that declares Jesus celibacy. But there has been a Sensus Fidelium an therefore it is an infallible teaching. Now if a bunch of modernists following Dan Brown decide to creat a "Jesus was married" movement, it would not matter, because there was a time where there was a Sensus Fidelium, and that makes it an infallible position that cannot change.

The same is true for life on other planets.

  • It is an issue that affect the faith and morals of Catholicism and therefore it is not purely a scientific question.
  • For 1800 years the entire Sensus Fidelium
    • Man alone bears the Divine Image and is unique in the universe
    • No intelligent corporeal creatures exist besides human beings
    • A “man” is a rational animal
    • All “men” are descendants of Adam and Eve, who were two literal people who lived on earth several thousand years ago.
  • Therefore, it is true.

This is how Sensus Fidelium works!

ET Promoters like to say this is purely a "scientific issue" like Geocentrism vs Heliocentricism. There is a clear difference. There is no impact of theology, whether the earth revolves around the sun or vice versa. As far as affecting Christian “matters of belief” (CCC, §92).

But every honest ET promoter admits that the "discovery" of rational aliens, especially if visiting earth, would be a theological earthquake. Therefore, it affects the faith an is subject to Sensus Fidelium. Catholic Et promoter and Theology professor Joel Parkyn says the discovery wiill cause:

.... may wholly redefine many of our conceptions of God and creation ...

a profound reformulation or recontextualizing of theology, requiring it to be expanded to accommodate a new Exotheology—representing the next phase of Christian theological research. The ramifications for Christian theology are myriad.[50]

Richard Rohr basically says this earthquake will turn the Bible into rubble.

Therefore, if we can determine that, at any point in the Church’s history, the faithful were unanimous in their belief that aliens do not exist, then it is an infallible fact that aliens do not exist.


Matt Fradd asked Jimmy Akin about Mary as the greatest creature in heaven, higher than the angels in Grace. How could a Jesus on another planet have another Mother of God. Jimmy Akin replies:

... someone might say that the deposit of Revelation ... establishes that our Virgin Mary is the highest anywhere in any timeline in any cosmos, in which case ... if there are other mothers of Jesus out there then well then they wouldn't be as high as our Mary ...I think ... the people who formulated these statements about Mary were not even contemplating that.

The Blessed Virgin Mary is a “mere mortal” like us; an entirely human person (unlike her Son, she was not Divine); a woman who was conceived and born, on earth, to a human mother and a human father just as we are (though Immaculately). But it is nevertheless settled that she is the supremely exalted creature. One so exalted, in fact, that it would be materially heretical to even propose the possibility of the existence of a created being that surpasses her.

Jimmy Akin is promoting the idea that there are alien civilizations far more advanced than us. But for some reason, their Mother Mary is inferior to ours, because our Dogma says our Mary is the highest, and yet these aliens have come to our earth to teach us how to live in peace and harmony.

This is an eye roller on several levels, and I think Jimmy realizes that. So his alternative to that is that:

... the people who formulated these statements about Mary were not even contemplating that [the possibility of aliens].

Jimmy Akin is asserting that since the Catholics in the first centuries weren't contemplating aliens, they mistakenly said Mary is "Queen of the Universe" instead of "Queen of Earth".

The Holy Spirit is behind Catholic Dogma and Sacred Tradition. The Holy Spirit knew what He was doing when the Church adopted the title Queen of the Universe for Mary, which was common as early as the 300's.


The unique and supreme positions held by Jesus and Mary dispute the possibility of aliens, but so does the glory of St. Joseph. Pope Leo XIII, in an encyclical towards the end of the 19th century, declared:

St. Joseph has been proclaimed Patron of the Church, and from [him] the Church looks for singular benefit from his patronage and protection ... In truth, the dignity of the Mother of God is so lofty that naught created can rank above it. But as Joseph has been united to the Blessed Virgin by the ties of marriage, it may not be doubted that he approached nearer than any to the eminent dignity by which the Mother of God surpasses so nobly all created natures. For marriage is the most intimate of all unions which from its essence imparts a community of gifts between those that by it are joined together. Thus in giving Joseph the Blessed Virgin as spouse, God appointed him to be ... a participator in her sublime dignity. (Quamquam Pluries, §3)

St. Joseph—unlike his spouse—was not immaculately conceived. From the beginning of its existence, therefore, his nature was entirely like our own. Nevertheless, we are authoritatively taught here that absolutely no creature, other than Mary, can be regarded as having the “eminent dignity” of St. Joseph.

The Encyclical teaches that “all created natures,” other than Mary’s, are beneath Joseph’s, thereby deliberately including extraterrestrial angels in its domain. From this, too, it follows that there are no aliens. St. Joseph is the Patron of the Universal Church. He is the Terror of Demons. Yet, he is an earthling.

The Church Fathers

There was plenty of belief in aliens among pagan and pre-christian religions, including Greek Atomists philosophers, Democritus (born 460 B.C.), Leucippus (born 510 B.C.), Epicureans (Born 341 B.C.) and later Roman thinkers, such as the poet Lucretius.

Greek philosphers with legacies of moral and spiritual destruction (the atheistic Atomists and hedonistic Epicureans) believed in extraterrestrials, the nobler philosophers had no use for such theories—Plato and Aristotle even explicitly condemned the notion of multiple inhabited worlds!

The Church Fathers were well aware of these beliefs and all of them who dealt with the issue rejected the idea, except Origen. Still, all those who do consider the many-earths question, even if only implicitly, all give a negative answer.

Polygenism is inadmissable

Some ET promoters recognize that there is no way to get around the Magisterial teaching that only Man can know and love God, mentioned above. So they say aliens fit the definition of "man". Here their definition runs aground on the dogma against polygenism.

The Bible says:

“Blessed are you, O God of our fathers, praised be your name forever and ever. Let the heavens and all your creation praise you forever. You made Adam and you gave him his wife Eve to be his help and support; and from these two the human race descended.” —Tobit 8:5-6

We have already considered Paragraph 26 of the Papal Encyclical Humani Generis, so let us now consider another passage:

When, however, there is question of another conjectural opinion, namely polygenism, the children of the Church by no means enjoy such liberty [of discussion]. For the faithful cannot embrace that opinion which maintains that either after Adam there existed on this earth true men who did not take their origin through natural generation from him as from the first parent of all, or that Adam represents a certain number of first parents. (§37)

The Mass

Pope Benedict XVI said:

Christian worship is surely a cosmic liturgy, which embraces both heaven and earth... It is precisely this cosmic dimension that is essential to Christian liturgy. It is never performed solely in the self-made world of man. It is always a cosmic liturgy. The theme of creation is embedded in Christian prayer. (Pope Benedict XVI. The Spirit of the Liturgy. Ch. 1,2)

The Mass asserts man's dominion over all creatures

You formed man in your own image and entrusted the whole world to his care, so that in serving you alone, the Creator, he might have dominion over all creatures. (Eucharistic Prayer IV)

There is not even a single line anywhere in the public prayer of the Church which gives grounds to speculate about such a possibility. The Church has always been very bold and would not shy away from praying God's Children on other planets if they were there. On the other hand it would be negligent to not include them in the Mass if they existed.

The Saints

There are 1,600 Canonizaed Saints through the new process, and about 11,000 Catholic saints in total. Many more are working their way through the process from Venerable, blessed, and finally Canonized. There are no references or revelations about aliens. On the other hand there are many clear statements about humans being the only rational creatures and about angels populating the cosmos, not aliens.

A final word from the 1st Vatican Council

... every assertion contrary to the truth of enlightened faith is totally false (Ch. 4 6,7) All faithful Christians are forbidden to defend as the legitimate conclusions of science those opinions which are known to be contrary to the doctrine of faith ... anathema. (Vatican I, 3039 DS 1818. 3)