According to Jim Still, “There is a unique theological conundrum here for Christians that Jews and Muslims escape: of what value is the incarnation if there are thousands (perhaps millions) of other worlds in the universe with intelligent life? Perhaps there were multiple incarnations—a million deaths on a million crosses—in a sort of macabre cosmological Groundhog Day.”
It’s hard to see how this is supposed to pose any sort of theological conundrum for Christianity. Either the human race would be the only fallen species, or else there would be other fallen species that God did not redeem.
In fact, we have a partial parallel in Scripture between elect angels who never fell, and fallen angels who were never redeemed.
Mr. Still follows this up with a superficial critique of penal substitution. But in so doing he has changed the subject from a theological conundrum allegedly generated by the hypothetical existence of ETs to the inner logic of the atonement. That’s a separate issue entirely.