Here's the answers from my personal point of view (no offence intended to those that believe differently):
1) According to Christians, God came to earth and was born as Jesus. Apparently he did some miracles (the Jews of the time accused him of sorcery as can be seen in their scriptures as well as in Christian scriptures, thus we can assume that he actually did do some supernatural things). Yet atheists still don't believe in God. So it seems that there was some proof that God exists (and there probably still is some proof) but once you decide that you don't want to believe in God... well, there's not really much even God can do!
2) I would say that the way ancient Jews, Muslims or Christians treated women is more of a cultural thing than a religious thing. Even today so-called believers justify their abuse of human rights by pointing to religious scripture. One must keep in mind that religious scripture was very much used to govern people in the old days. For instance, Christianity was designed by the Roman Empire to prevent conflict between rival religions. It was designed to suit everybody rather than any specific religious sect. Christianity was a compromise. So people tend to develop their religions to fit into their social ideologies or social needs rather than the other way around.
3) There's an ancient Sufi saying: "God sleeps in the rock, dreams in the plant, stirs in the animal and awakens in man." Anyone can be his own prophet. There's a voice of reason within every person that can guide that person to realise his/her full potential to be a happy person (or animal). However, some people do not know how to tap into that voice of reason. I believe that the prophets of old were no more than philosophers and great thinkers. They were able to analyze situations on a grand scale and make accurate predictions at times. However, sometimes they also spoke in meaningless riddles. Nostradamus had a knack for this as well. The predictions he made were so abstract that it could have meant anything. We are the ones that validate those predictions when we say: "Oh, yeah! So the rock he spoke about was actually a comet and the bones of the beast was the dinosaurs!"
To conclude: to believe in God, is a personal decision. All the various religions are other people's ideas of God. I think one should ask: "If God exists, how would I imagine Him?" For in the end, if God exists, we are all creations that were formed out of Him. We should thus have a pretty good idea how He would like us to act and what He wants us to believe. I guess it's a question of guilt. What makes you feel more guilty? Believing in God or not believing in God?
Go for the believe that makes you feel less quilty, whatever that may be. For my part, not believing in God makes me feel empty and meaningless. But that's me.
