I don't get this whole religion thing with you people?

All the religions have a supreme being, i.e. God, Zues, etc. a son. i.e. Jesus, Hercules. and people who do their work. i.e. Angels and gods and goddesses etc. Whys is it that people are so dead set in what they believe in that they don't see it's all similar in some way? Also if someone believes in something else and it doesn't go by the "rules" then they are quick to persecute?