Why is it that Christians always believe they're right...?

I don't asks atheists to prove that God does not exist because to me, that would be impossible for them to do just as it would be impossible for me to prove to them that He does exist. As for the Bible, it's not literal. I do accept that it is in no way infallible being as it was written, translated and edited by men. Also there were more stories left out of the New Testament than were included. But the basic principles of the Bible are what I live by.