I don't think they're refusing to believe it themselves. It's more like, if you will, like another Nazi once said:
“Why of course the people don't want war. Why should some poor slob on a farm want to risk his life in a war when the best he can get out of it is to come back to his farm in one piece? Naturally the common people don't want war: neither in Russia, nor in England, nor for that matter in Germany. That is understood. But after all it is the leaders of a country who determine the policy and it is always a simple matter to drag the people along, whether it is a democracy or fascist dictorship, or a parliament or a communist dictatorship. Voice or no voice, the people can always be brought to the bidding of the leaders. That is easy. All you have to do is tell them they are being attacked, and denounce the peace makers for lack of patriotism and exposing the country to danger. It works the same in any country.”
― Hermann Goering
Seems to me like basically that's what these chucklenuts are doing: painting it as, no, see it's Germany that was under attack, and denounce those who were actually trying to achieve some peace on the continent.