- Not to be confused are UFO religions or ancient astronaut theories that posit that historical religious scripture or mythology was inspired by visits from extraterrestrials.
- "Exotheism" is a fictional denomination in the Vampire: The Requiem role-playing game.
The term "exotheology" was coined in the 1960s or early 1970s for the examination of theological issues as they pertain to extraterrestrial intelligence. It is primarily concerned with either conjecture about possible theological beliefs that extraterrestrials might have, or how our own theologies have been or will be influenced by evidence of and/or interaction with extraterrestrials. One of the main themes of Exotheology is applying the concept the possibility of extraterrestrials who are sentient, and more to the point, endowed with a soul, as a thought experiment to the examination of a given theology, mostly Christian theology, occasionally also Jewish theology.
A Christian writer early to address the question was C. S. Lewis (1898–1963) who in a 1950s article in the Christian Herald contemplated the possibility of the Son of God incarnating in other, extraterrestrial, worlds, or else that God could devise an entirely distinct plan of salvation for extraterrestrial communities from the one applicable to humans.
Lutheran apologist Ted Peters (2003) asserts that the questions raised by the possibility of extraterrestrial life are by no means new to Christian theology and by no means pose, as asserted by other authors, a threat for Christian dogma. Peters points out that medieval theology had frequently considered the question of "what if God had created many worlds?", as early as the discussion of the Antipodes by the Church Fathers.
The Catholic Vatican theologian Corrado Balducci often discussed the question in Italian popular media, and in 2001 published a statement UFOs and Extraterrestrials - A Problem for the Church? In a 2008 statement, José Gabriel Funes, head of the Vatican Observatory, said "Just as there is a multiplicity of creatures on earth, there can be other beings, even intelligent, created by God. This is not in contrast with our faith because we can't put limits on God's creative freedom".
Rabbi Aryeh Kaplan, who was also a physicist, was inclined toward the belief in extraterrestrial life, citing various classic Jewish authorities. Among them are the medieval philosopher Rabbi Chasdai Crescas (Ohr Hashem 4:2) and 18th century kabbalist Rabbi Pinchas Eliyahu Horowitz (Sefer HaBris). After presenting his sources, Rabbi Kaplan remarks, "We therefore find the basic thesis of the Sefer HaBris supported by a number of clear-cut statements by our Sages. There may even be other forms of intelligent life in the universe, but such life forms do not have free will, and therefore do not have moral responsibility"—at least in the same sense as human beings.
Rabbi Norman Lamm, former chancellor of Yeshiva University, has also written on this subject, asserting that if the existence of extraterrestrial life should be confirmed, religious scholars must revise previous assumptions to the contrary. He, too, does not rule out this possibility from an Orthodox Jewish point of view.
- An early attestation is the title "A Jewish Exotheology" in Norman Lamm, Faith and Doubt: Studies in Traditional Jewish Thought, Ktav Pub. House, 1971, p. 107.
- "Dabbling in Exotheology". Time (magazine). 1978-04-24. Retrieved 2007-05-10.
- Vatican scientist says belief in God and aliens is OK Reuters, May 14, 2008 Pope's astronomer insists alien life 'would be part of God's creation', The Independent, 15th May 2008.
- [Aryeh Kaplan. "On Extraterrestrial Life."] The Aryeh Kaplan Reader, Artscroll/Mesorah Publications.
- "A Jewish Exotheology," published as Chapter 5 in Norman Lamm, Faith and doubt: studies in traditional Jewish thought, Ktav Pub. House, 1971, p. 107.
- Thomas F. O'Meara, O.P. “Christian Theology and Extraterrestrial Intelligent Life.” Theological Studies 60 (1999): 3-30.
- Ted Peters, Science, theology, and ethics, Ashgate science and religion series, 2003, ISBN 978-0-7546-0825-7, chapter 6: "Exotheology: Speculations on Extraterrestrial Life"