What about extraterrestrials? Has anyone written about the theological implications if they exist? Do they need salvation? If so, did Jesus, at various times, come down from heaven and go to their planets to die for their sins, or does his death on earth give them salvation too? If it does, and he never went to their planets, how do they know about Him and the Father?
The late Ray Bradbury wrote a classic science fiction short story about this concept, “The Man.” I believe it’s contained in his anthology “The Illustrated Man.” I recommend it.
Regarding the question of whether aliens would have a soul or be “mere” animals, who knows? It wasn’t considered to be necessary for our salvation for this to be revealed.
An interesting treatment of this in literature is in the James Blish novel, “A Case of Conscience.” In the novel, a Jesuit geologist on a planetary survey team has been one of the first to make contact with an intelligent alien species. They are large, bipedal lizards that resemble dinosaurs, but are intelligent, kindly, and gentle. They evince all the virtues save piety and faith - they have no concept of religion or God. The other secular members of the survey team have no problem with this, but the Spanish priest begins to suspect something more sinister - that the entire planet and all on it was created by Satan as a final blow against the Faith and the destruction of his people. He argues that the entire planet should be placed under quarantine, which the rest of the team of course rejects.
The priest also confesses to the rest of the team that in making this claim, he has excommunicated himself,
latae sententiae, in that he has accepted into his soul the gnostic heresy that Satan can create, a power that only God holds in Catholic teaching. The Jesuit has to return home and present himself before the head of his order and the Pope, on the same ship that will bring an embryonic form of the aliens back to Earth to grow to maturity on an unstable and overpopulated earth, and who may itself be the Antichrist. The solution of the priest’s moral dilemma at the end of the novel is fascinating.
It’s an interesting novel that takes Catholic theology seriously (long sections of the novel are essentially a theological debate), and which I also recommend.
For another literary take on the theological implications of extraterrestrial life, check out the 1950s film “Red Planet” with Peter Graves - it’s available on streaming Netflix if you have it. In the near future, a scientist establishes contact with intelligent life on Mars (okay, the science is a little dated) and learns that the Martians believe in God, and Jesus, and have a culture based on living in accordance with His design. This discovery leads to worldwide change - mass conversions and the collapse of the Soviet Union. But is all what it seems? Interesting movie, not too heavy-handed.