Christian scholars like Dr. Peters and indeed the pope agree that the possibility of redemption probably extends to all of creation, even perhaps the inanimate world.

“How could he be God and leave extraterrestrials in sin?” asks the Rev. George V. Coyne, the former director of the Vatican Observatory and now a Jesuit priest who holds the McDevitt Chair of Religious Philosophy at Le Moyne College in Syracuse, in the 2000 book “Many Worlds: The New Universe, Extraterrestrial Life and the Theological Implications,” edited by the astronomer Steven J. Dick, a former chief historian for NASA. “After all, he was good to us. Why should he not be good to them?”

This has engendered a sort of how-many-angels-can-dance-on-the-head-of-a-pin argument about whether Christ died for the entire cosmos, or whether the son of God or the metaphysical equivalent has to be born and die on every populated planet.

Each alternative sounds ridiculous on the face of it. The first alternative would make Earth the center of the universe again, not just in space but in time, carrying the hopes for the salvation of beings that lived and died millions or billions of years ago and far, far away.

The second alternative would be multiple incarnations, requiring every civilization to have its own redeemer — “its own adventure with God,” in the words of Professor Peters. That is hardly better. As the old troublemaker Thomas Paine wrote in “The Age of Reason,” “In this case, the person who is irreverently called the son of God, and sometimes God himself, would have nothing else to do than to travel from world to world, in an endless succession of deaths, with scarcely a momentary interval of life.”

Distinguished theologians have come down on different sides of this issue; after all, it’s not up to us to say what God could or could not do. “God doesn’t seem to be limited by history and communication,” Dr. Peters said in an interview, playing the devil’s advocate, so to speak, for the notion of a single incarnation for the entire cosmos. In that case, the consequences would not be limited to “people who get emails about it.”

“Every sentient being is blessed by God’s grace whether they know about it or not,” he said.

Seeking scientific as well as spiritual guidance, I dialed up Guy Consolmagno at the Vatican Observatory. He is a Jesuit brother and a co-author, with his fellow Jesuit Paul Mueller, of “Would You Baptize an Extraterrestrial? ... And Other Questions from the Astronomer’s In-box at the Vatican Observatory.”