I'm sure that Hitler had heard of Jesus and was told about him. With all the Christians he had to deal with, who were helping hide the Jews, I'm sure if he wanted to he could've met Jesus, not in the same way Paul did but the way that one who accepts Him into their heart does.
Paul heard of Jesus as well, but continued to persecute Christians. It wasn't until he saw him with his own eyes in a miraculous event that he changed his ways. Hitler was never given that chance.
However, like John 15:24 says: "If I had not done among them the works which no one else did, they would have no sin; but now they have seen and also hated both Me and My Father." No matter what Jesus shows them, they will still not believe. There were thousands and thousands and millions and millions of people who saw Jesus' miracles but didn't belive in Him. When Jesus appeared to Paul it was miraculous, but Paul could still have kept a hard heart and continued killing Christians or at least not turn to Jesus.
Paul could have stayed the same, but the fact is he did change. Countless people did witness Jesus and did not change. However, my point is that if even one person did change, would it not be worth it ? If Jesus appeared today in a miraculous event to the 6 billion people living today and only one person changed his wayward life, would it not be worth it ? (if he really does care about us, that is) 4 "What man of YOU with a hundred sheep, on losing one of them, will not leave the ninety-nine behind in the wilderness and go for the lost one until he finds it?" (Luke 15:4)
"[God] does not desire any to be destroyed but desires all to attain to repentance." (2 Peter 3:9) What's your take ? Golf -- What was your question again ?
-mE