The public, worldwide conversation about UFOs (also known as UAP) has become more widespread and mainstream in recent years. It presents Catholics with a challenge: Does the Church teach that angels are the only form of nonhuman intelligence created by God? Is belief in extraterrestrial intelligence (ETI) or other forms of nonhuman intelligence (NHI) contrary to the Catholic faith?
For essential context in this discussion, we must consider the history of the NHI conversation in the Catholic intellectual tradition. Have there been prominent, theologically faithful voices over the centuries who believed in NHI, or were at least open to the possibility of it, and saw no conflict between that notion and the truths of divine revelation?
There have been indeed.
Pre-Christian Greek philosophical ideas about the cosmos served largely as the “science” of the day for most Catholic thinkers in the ancient and medieval worlds. The two most influential Greek philosophers, Plato and Aristotle, insisted that the Earth was the center of a single universe, with the other heavenly bodies revolving around it. They thought Mars, Venus, and the other planets were wandering stars, with no concept of a planet as a rocky or gaseous ball on which life could exist. There was thus little room in the dominant ancient Western cosmology for extraterrestrial intelligence. Such creatures would have nowhere to live.
Even so, the possibility of two particular forms of ETI was admitted. Aristotle once suggested that the moon might be inhabited. Plato thought the stars were sentient beings with souls that moved their bodies across the sky. This latter notion of ETI was considered a reasonable possibility by St. Augustine (354-430), one of the greatest theologians of the ancient Church.
Not surprisingly, then, most Catholic thinkers who considered the matter throughout these centuries had no notion of intelligent life on other planets. But some believed in a different kind of nonhuman, non-angelic intelligence: They thought at least some of the pagan mythological figures, such as centaurs, satyrs, and fauns, actually existed. Among those who held this view were St. Augustine (City of God, XV, 23) and St. Jerome (347-420), the latter known as “the father of biblical scholarship.”
The medieval world was largely still under the influence of Aristotle, especially St. Thomas Aquinas (1225-1274). So he had no concept of planets as we know them, and thus no speculation about inhabited planets. He was open, however, as Augustine had been, to the ancient idea that the stars are intelligent living creatures, constituting a different form of ETI.
In the fifteenth century, one prominent Catholic thinker made a decisive turn from the ancient, earth-centered model of the cosmos. Nicholas of Cusa (1401-1464), a German theologian, philosopher, and astronomer, anticipated many aspects of modern cosmology. The universe has no center, he insisted; earth is only one planet among many; the heavenly bodies are made of the same basic elements as earth and (he speculated) most likely host intelligent species.
We might have expected Cusa’s rather radical break with philosophical tradition to provoke considerable opposition. Yet his appointment as a cardinal, a papal legate, and a papal adviser, and his participation in the General Council of Basel (1431), all suggest that within the Catholic Church, he was respected and embraced by authorities at the highest levels. Meanwhile, his contemporary, the French philosopher and theologian William of Vorilong (also known as Guillaume de Varouillon, ca. 1392-1463), was speculating about an infinity of inhabited planets.
In the following generation, Nicholas Copernicus (1473-1543), a Polish mathematician, astronomer, and doctor of canon law, sparked the famous “Copernican revolution” of the sixteenth century in science with his heliocentric (“sun-centered”) model of the cosmos. His findings implied that the planets have physical compositions similar to that of the earth. Though we have no record that Copernicus pondered their possible inhabitants, this new realization led many of his followers to propose the existence of ETI.
In the seventeenth century, the discoveries of the Catholic astronomer Galileo Galilei (1564-1642), after considerable controversy, opened the door to further speculation about ETI. In his Apology for Galileo (1633), the Dominican friar, theologian, and philosopher Tomasso Campanella (1568-1639) noted that no decree had ever been issued by the Church denying the possibility of other inhabited worlds. That notion was contrary to Aristotle, he said, not to Scripture.
Around the year 1700, the Italian exorcist Fr. Ludovico Sinistrari (1632?-1701) argued confidently that the Christian faith did not rule out extraterrestrial intelligence. He also cited approvingly the statements of Augustine and Jerome that affirmed the existence of non-angelic NHI, offering evidence from his personal experience and that of other exorcists that such creatures are real.
In the eighteenth century, the Croatian Jesuit priest, astronomer, physicist, and philosopher Roger Joseph Boscovich (1711-87) taught at the Collegium Romanum and the University of Padua. He proposed the existence of not only ETI, but entire parallel universes existing outside our own. His speculations foreshadowed in certain ways our modern theories about the possibility of a multiverse.
By the nineteenth century, the notion of extraterrestrial intelligence had become widespread among Catholic and other Christian theologians. Those who thought the existence of ETI to be certain, probable, or at least possible included prominent clergymen, religious, and theologians in France, Germany, Italy, Spain, and the United States. Among those best known in the U.S. were Fr. Joseph Pohle (1852-1922), a member of the founding faculty of The Catholic University of America in D.C. and author of Star Worlds and Their Inhabitants; Fr. George Mary Searle (1839-1918), director of the astronomical observatory of the same university; and Fr. Januarius De Concilio (1836-98), a college and seminary professor who attended the Third Plenary Council of Baltimore and played an essential role in creating the standard edition of the popular Baltimore Catechism.
In that same century, Ven. Andrea Beltrami (1870-97), an Italian Salesian priest who received the habit from St. John Bosco, reportedly prayed for the inhabitants of other planets and devoted one of sixteen books he wrote (yet unpublished) to the topic of ETI.
One last Catholic voice of the nineteenth century deserves mention. The celebrated German mystic and stigmatist Bl. Anne Catherine Emmerich (1774-1824) allegedly received private revelations throughout her lifetime, including visions of inhabited celestial bodies. Some have questioned whether the documents of her visions were altered. But we should note that for half a century after their publication, a number of eminent Catholic theologians who examined the documents apparently found no reason to doubt that the existence of the extraterrestrial creatures she reported would be in accord with the Church’s teaching.
In the early twentieth century, research into paranormal phenomena was one of the many interests of the English Jesuit Fr. Herbert Thurston (1856-1939). A prolific scholar, he made extensive contributions to the Catholic Encyclopedia, writing on spiritual, historical, liturgical, and literary subjects. Thurston came to conclusions similar to those of Sinistrari: Numerous cases brought to exorcists, he reasoned, seem to involve examples of NHI that are not demonic.
In the mid-twentieth century, a flurry of brief speculations about ETI by Christian theologians appeared in response to the beginning of the Space Age. The most energetic discussions of the possibility came from Catholic theologians, and the dominant position of this group was that belief in extraterrestrial intelligence is consistent both with science and with the teaching of the Church.
Later in the century, some highly intriguing references to ETI came from three canonized saints. According to the French Catholic philosopher and theologian Jean Guitton, Pope St. Paul VI (1897-1978) once told him that he found the possibility of ETI reasonable and could see how the universal Church could include such creatures. The renowned Italian Capuchin friar, priest, and mystic St. Pio of Pietrelcina (also known as Padre Pio, 1887-1968) once declared emphatically in private conversation that other beings exist on other planets who did not sin and fall as we did.
More recently, Pope St. John Paul II (1920-2005) was once asked in a public audience by a youngster, “Holy Father, are there any aliens?” Tellingly, the saint did not reply, “No, that would be contrary to our faith,” or “If they exist, then . . .” Instead, he said simply, “Always remember: They are children of God as we are.” (This anecdote is reported by Msgr. Corrado Balducci in “Ufology and Theological Clarifications,” remarks presented at Pescara, Italy, June 8, 2001.)
The Holy Father’s reply is especially important for the debate about what the Catechism of the Catholic Church teaches about ETI. He was the pope who commissioned the Catechism and oversaw its creation, and then approved, promulgated, and warmly endorsed it in an apostolic letter. Who could be a more reliable interpreter of its meaning?
If this pope had believed that the existence of ETI is contrary to the Catholic faith and the teaching of the Catechism, he would have been obliged to say so to the youngster, and to all in the audience that day. To do otherwise would have been to mislead them.
All these faithful Catholic voices from across the centuries obviously don’t prove the existence of non-angelic, nonhuman intelligence. We should also note that other theologians throughout history have argued against such possibilities. But this brief historical survey does demonstrate that many highly regarded Catholic thinkers have concluded that the existence of such NHI would not be contrary to the Catholic faith.
For an-depth treatment of this topic with documentation of sources, see Paul Thigpen, Extraterrestrial Intelligence and the Catholic Faith: Are We Alone in the Universe with God and the Angels? (TAN Books, 2022); “NHI, UAP, and the Catholic Faith: How Will the Church Respond?” Sol Foundation White Papers, Vol. 1, No. 5 (July 2024); “A Very Short History of the Catholic Debates About the Multiverse and Extraterrestrial Intelligence,” Church Life Journal, March 12, 2024.