I'd like to point out that this is not neccessarily a bad thing- the major monotheistic religions (judaism, christianatity, and Islam) each recognize the others beliefs to an extent, and say that even devotees from other religions can still get to heaven, implying that while each religion believes itself to be more right, being a good person and believing in a higher power are the prime factors in determining whether a person will get to heaven,giving theist agnostics a good chance of getting into heaven (if they are moral people, obviously.)
edit: concerning free will, altbough I don't know if there is a legitimate "normal" proof of it, the theist proof is "god=omnipotent" "god says there is free will," "q.e.d. there is free will," once you take take omnipotence into account, most paradoxes about religion vanish, although this only works for paradoxes.