Why do people believe in god, and why are there different religions?

and why do people from one religion think that other religions are wrong or that their religion is the best one, and why do religious people often try to persuade others (like me) that they should become religious? Is it not dangerous to hold beliefs so strongly? Will religion ever cease to exist? If so will we have a more peaceful world? I know a lot of nice religious people, so I don't have a problem with them. My problem is that I don't understand this at all, and I can't in any way relate to the idea that there is something like a god anywhere except in the minds of people here and there, and some of them seem not to be very wise and reflective people who have just accepted these beliefs because they were taught them as children. Please help.