Hi I'm not a Christian, but I'm not an atheist. Much of how atheism is practically manifested online and in forums is heavily biased by people's personal issues and emotional sentiments. Hitler being a Christian or not has nothing to do with the truth value of a philosophical/religious argument.

The Nazi party heavily invested in highway infrastructure, were way ahead of their time in attitudes towards smoking and tobacco, and there's significant historical suggestions that Hitler approved of vegetarianism and loved animals. So, are building highways, banning smoking, and loving animals bad things? No.

The best thing to do when you notice the person you're discussing with is heavily emotional is to disengage.

"I hate blue. Blue is a stupid color. It's horrible".. "I think that the sky is more blue than it is grey" - these two people can't have a conversation. Best for one of them to walk away.