Evolution is neither theistic nor atheistic. It is a natural phenomenon which has nothing to do with beliefs.
It continues to amaze me as how even some very intelligent theologians are opposed to evolution for religious reasons (e.g. a Cardinal I knew and highly respected during my years in Rome).
Evolution is fully compatible with theism and creationism, for if a God can create the Universe, the same God can create a Universe that evolves.
Evolution is just as fully compatible with atheism, or at least I don't see too many (if any) atheists that have a problem with it.
IMHO people so opposed to evolution are really opposed to Darwinism, especially the popular version of Darwinism, namely that humans evolved from monkeys (which is not what Darwin said).
I have recently witnessed a heated debate in a restaurant, where someone was strongly opposed to evolution because "Monkeys are not my cousins." Emotional arguments, nothing to do with observation of natural phenomena.
Anyway, Darwinism and evolution are not the same. Evolution is a phenomenon, Darwinism is a theory (one of many, at that) about said phenomenon.