Why does determinism not disprove religion?
Because there is nothing about religion that is testable; in other words, religion cannot be disproven at all, not just when compared with determinism. For that matter, determinism is a broad and general theory, or perhaps philosophy, that itself is rather difficult to test on a scale comparable to something like religion. On a much smaller scale, determinism is really the nature of many research conclusions. For example, it can be determined that heating a gas will cause its volume to increase.