You know what really convinces me that there really is a God. Life. The unfairness of life is what convinces me. Life sucks. There's war, hunger, poverty, chaos, unfairness, and just the brokenness of mankind. I know some people think that's proof that God doesn't exist, but it's really the opposite. Think about it.
There has to be more. There must be something, or someone, who will even everything out. Otherwise, what hope do we have? If you take away that hope, what's the use of living?