Why is it so important for people to prove that God exists?

Actually, I think it's WAY more important for atheists that the religious side proves their gods. Atheists can't accept the fact that faith is enough.

There are religious people — many of the scientists — who are rationally-minded enough to want to find definitive proof for god in science, or at least explanations for mutual compatibility. And there is some convincing evidence there — read The Language of God if you haven't. It is written by Francis Collins, the leader of the Human Genome project, and it advocates theistic evolution. It didn't convert me but presented me with some interesting ideas for sure.

Faith, though, is the core of all religion. If you believe there is a god, there is no reason to prove it. I was raised in a mostly nonreligious environment, so atheism came naturally to me. I was atheist as a child far before I rationally considered all the evidence for and against God.

People are sometimes confused and want to contrast religious people and atheists. They are both worldviews, and each relies on some form of fate. Atheists can be irrational, and religious people can be very rational. I know a few here on Quora — and they stand out as far more intelligent than the average atheist crusader here on the site.