Proof is never enough for the man who refuses to be persuaded. If a person does not want something to be true bad enough, no amount of proof will change their mind. That person will never acquiesce to truth.
Some Christians think they have to prove that there's a God. But, God doesn't command us to prove His existence. God says in Romans that everything He has created proves His existence and no man has a legitimate excuse to doubt His existence. We are called to preach the good news of Jesus and the good news of the kingdom of God. Trying to prove God's existence is unnecessary and, as far as some people are concerned, impossible.
If there is a God, then He has the right to make demands upon His creations. He has the right to rule over them. If a person doesn't want to be ruled over, then that person doesn't want there to be a God who can rule over them and therefore will not accept your proof of God no matter how legitimate or compelling it is.
Tell people the good news of Jesus the Christ and let the Holy Spirit do His part. He is the one responsible for convicting the world of sin, not you or me. Pray and preach, leave the rest to God.