This world does a good job of abusing its creatures without our help. A huge part of life is taking abuse and sufferring.
I think hope can be taught without unlikely hypotheticals. I dont believe that just chanting some magic words grants you a free pass. Hitler would have to really understand it and embrace it. Somebody who could do the things that he did is so removed from God that I truly dont see this happening.
The Old Testament at the very least makes it clear that not everybody can be convinced. There is also some unsavory bits about how problem people like Hitler should be dealt with brutally and efficiently but I digress.
Is it possible? Sure. Likely? Almost certainly not. Dont think of salvation as something being done to a person. It is something we do for ourselves. God is less a person and more a force of nature. He doesn’t do things to people so much as people embrace him.
This helps me see it in a positive way. Preachers can teach Hope and Forgiveness without this offputting and misleading hypothetical in my opinion.