What if God is too big to be defined by just one religion?
I think we have different religions because, just like you say there are so many different people in the world. The Bible says God is not willing for any to perish (or not be saved or something like that). If that's true then it would be strange that he sends all the Angels and prophets to just one small country. I think that he shows himself to anyone who seeks, anywhere. I think he answers the questions we ask.
Different religions exist (and different denominations) because different people ask different questions. The mistatke is that they turn around (or their followers) and institute this "one and only truth, we have all the answers" stuff.