I've heard from many Christians (and Muslims too) that other adepts who believe slightly differently are not true, real Christians / Muslims. Every time a member of an organization does something outrageous all his organizations rush to say that this person wasn't their "real" member. A striking recent example is Anders Behring Breivik. Look what his church, lodge, party said. So yesterday he was their member and his line of thoughts probably was OK with at least some other members. But he followed it to the logical end and committed a horrific crime. Immediately they have nothing to do with him.
Hitler certainly posed with Christians and their churches whatever his true beliefs were. Presumably he thought it would help his image and popularity. Lots of political leaders since Constantine used Christianity in the same way. There were Christians and their clerics supporting Hitler. See here or here. IT WAS POSSIBLE. Would it be possible with Humanists / Humanism or Pacifists / Pacifism? That what the text under the middle photo ("Christianity is a religion of peace") really meant in my opinion.