I don’t think there is anyone living who knows with complete certainty that God exists. Likewise, God’s existence cannot be disproven either. I have yet to read all 50 of the supposed proofs on this site, but of those I have read, I would call them thought-provoking, at best. For example, proof #10 (godisimaginary.com/i10.htm
) questions the need of God for money and his need for people to provide it in order that his will may be done. The Christian answer is that God does not need money, and could, in fact, cause it to rain turkey sandwiches for the poor if He wanted to. What God wants is to build in people the quality of charity, among other things. Paying a tithe is one way God instills in us that quality.