Does God exist?

If you believe God exists, you gain everything. If you disbelieve, and God exists, you lose everything.

Alternately: It makes more sense to believe in God than to not believe. If you believe and, God exists, you will be rewarded in the afterlife. If you do not believe, and he exists, you will be punished for your disbelief. If He does not exist, you have lost nothing either way.