Is the theory of evolution "inherently atheistic"? Why or why not?

No. But believers get confused. They believe that just because not a single scientific theory or law includes God, which is due to the fact that everything can be explained without including God, that this means people who accept the theory of evolution are atheists. I would probably guess that most are atheists simply because they realize that a God is not needed to understand the universe or any part of it. But this doesn't make the theory of evolution "inherently atheistic".