Bad example. Everyone exists had to have a great, great, great grandfather. How else would you be alive? You obviously can't refute that, that would be idiotic.
I can rule out that he doens't exist by:
1. there is no hard proof evidence (you'd think after thousands of years you'd be able to see some evidence)
2. All the suffering of good people in the world
3. All of the good things that happen to bad people in the world
4. AIDS
5. Cancer
6. All of the lives killed in the name of god (HUGE list)
7. The fact that such a powerful being has dumb human emotions like jealousy over gods that he knows don't exist.
8. The corruption of the church.
9. That religion was created.
10. That all of the people who don't believe in him are cast into hell, yet he is merciful.
11. Science can explain the origin of life and the universe. (mostly)
12. How ignorant religious people are, thinking they KNOW they are right.
13. All of the other religions in the world, what makes that single one the right religion?
14. The bible is full of contradictions and a mad god.
15. The ten commandments don't include more important things to be obeyed like rape.
16. The bigotry caused by religion. (ex. against gays)
17. People don't just come back to life after being dead.
18. You can't have a baby if you're a virgin.
19. That all of the people before Christianity were cast into hell because they had no idea Christianity was even going to be created.
20. All of the above and more...
As you can see, I could go on and on and on...
Those are just a tiny few reasons i don't believe in god. That is my "proof."