IMO, if God exists it’s nothing at all like what any religion says. If a god exists at all, there are only two possibilities I think it could be:
Non-intelligent happenstance. The universe itself. The laws of physics. Whatever; it’s a concept and not a literal entity.
An intelligence that created humans and/or other life here or there, but is not really “God” in anyway described by man. They’re just highly intelligent beings that bioengineered us long, long ago.
The existence of an afterlife though is more complicated. There’s two possibilities, at least IMO:
There is nothing after death. No soul that lives on or moves on. There is just the meat in our skull hallucinating things based on external stimuli from reality to make sense of it all until the electrical signals stop and we cease to exist.
There is something beyond current understanding where consciousness comes from and it can exist in some form after death. Whatever it experiences after death would be something of an afterlife; though it is probably nothing at all like what any religion describes. It may not even be possible to describe it at all because it’s just super weird.