i've given this some thought in the past as i have a vast imagination, coupled with far too much time on my hands.
i came to the conclusion that if sentient creatures not from earth(aliens) do in fact exist and live and die the same as us that they may all go to
the same "heaven" that some of us believe in.
my opinion is that (speaking solely from the point of view of christianity, which the OP seemed to be pointing toward) god sent jesus to us. he was
our gift, our salvation
OUR gift
OUR salvation
for the human race, he was our redeemer and so that is our truth
i think that possibly the hypothetical alien beings could perhaps have their own means of salvation. a means of salvation separate and possibly far
different than our own.
we have to keep in mind, if god exists in the omnipotent and immortal form that biblical references attribute this fine deity, then we have to wrap
our mind around the idea that just maybe things we cannot ever truly understand whip around gods noggin and quick as a flash, poof into existence. if
that is so then maybe god created a race of beings with entirely different character flaws and means of self destruction and so therefore they require
a wholly different means by which to save their souls and brings themselves closer to their creator.