Well, what (~A ->…
Well, what (~A -> ~P) -> G says is: “God exists if: it’s the case that my prayers aren’t answered (by God) only if I don’t pray.” But that does intuitively imply that God exists: prayers can only be answered (the way we’re using that term) if God does in fact exist.
So I don’t see the problem at this point.
Of course, there is a problem with the idea that truth-functional material implication expresses the same thing as an English “if-then” or “only if” phrase.