What makes any religion more right then other religions?

All religions have similiar facts "proving" their religion is the true one, all with their own doctorine, beliefs and religious practices. and they claim to be the correct one and all others are not. What makes god and jesus anymore real then zues and herculues, or what makes the teachings of mohammed any more real then the norse legends and stories. Why is everyone who practices a certain relgion athiest to all other relgions to the point where they dismiss the other religions as fables, stories, and things people in ancient times believed in, when their own religion has just as much proof as those past religions.