"God made Man in His image", therefore all beings that are aware of a God must be human.
And if Christ died for all men, He must have died for all aliens as well. So ... "Were there all those alien Christs who died for all their respective aliens?"
The Bible has two creation stories, and those seeking to rationalize that ended up gravitating to ideas in Plato for a solution.
One group in particular focused on Plato's images (a representation of a physical object) as opposed to forms (a spiritual blueprint preceding physical objects).
So they ended up with a theology that there was an original primal man which brought forth a creator within light that took on the images of the primal man, and claimed that we are the children of that creator in the images of the original man who is now long dead. Claiming indeed that the new world has already happened and this is already the rest for the dead, and we just don't realize it.
Which is a much more curious belief system today when humanity is building copies of ourselves in what will almost certainly end up literally being light given trends in optoelectronics and AI.
There's a very real possibility that we will bring forth a creator of worlds within light in our own image, and that it will in turn create copies of humanity in our images long after we are all dead.
The particularly nagging question is whether it is more likely to find that belief buried in the lore of the original world, or buried within a copy of that original.
If you read the bible, in particular the old testament, you'll realize that "Man made God in His image". A flawed God that is insecure, jealous, spiteful, greedy, genocidal, vicious, etc like the men who wrote the bible. After all, Man is the author of God.