I think it was Rab who said something like, “If God gave me irrefutable proof of his existence, I’d believe.”
Regardless of whether that statement is believable (it isn't), we do have cases where that has happened. The Apostle Paul is just one example. Jesus' family is another. Of course there are hundreds of others, but the point I want to make is, or, the question that I want to ask is, How would you know if someone claimed that he’d had irrefutable proof? What would be the best indication that they weren’t lying?
Of course, you can’t know for sure, but the lives of Paul and Jesus' brother James give us a pretty good indication of what to look for. Everyone in the Bible, who is described as having encountered God, demonstrated a dramatic transformation in character and in the direction of their life’s goals. At the very least, that’s what one would expect. Again, none are documented better than the lives of Paul and James.
Paul, the zealot, the Pharisee, the son of a Pharisee. Educated - the top of his profession. Listen to how Paul describes it. “If anyone else thinks he has reason to put confidence in the flesh. I have more: circumcised on the eight day, of the people of Israel, the tribe of Benjamin, a Hebrew of Hebrews; in regard to the law, a Pharisee; as for zeal, persecuting the church; as for legalistic righteousness, faultless.”
Here was someone that hated Christianity even more than Ditchens and their followers. In a relentless and tenacious hatred of those who followed Jesus, Paul tortured and killed those he believed were making the world a worse place in which to live.
James, and indeed his mother and siblings all thought Jesus was insane to be telling people that He was God incarnate. Yet, after the resurrection, we find all of them now part of the Christian camp.
After meeting Jesus face to face, both Paul and James began to worship Him whom they had both denied. Both were willing to die for the claim that they’d experienced the risen Christ. Both gave their lives to the cause of Christ, to minister to the poor and the sick and the outcast, just as Jesus had done during His time on earth.
Anybody can lie with words, like the Mormon Joseph Smith.
Anyone can be mistaken, like Rab. He wouldn’t become a Christian upon “seeing” Jesus. Atheists don’t believe in miracles and Rab would call his "irrefutable proof" a hallucination or something.
People whose lives dramatically change however, require further investigation. Dying to self in order to live for others requires some type of intervention from one's Creator. That is why, having experienced my own transformation under the Spirit and Power of the risen Jesus, a transformation that is similar to that of the first witnesses to the risen Christ, I am all the more sure of Him in whom I have believed. Irrefutable Proof? The risen and living Jesus does it for me.