Fact, every single german nazi was a christian

[abaris]

Their atheism certainly had a role in that, insofar as they believed (correctly, in my view) that religion was (and is) a brake on man's progress.

That was certainly Marx' general idea when he penned down his famous quote, which has to be read in context to get the whole meaning. He more or less says that religion is used by the powerful to hold the masses down and in line. That was certainly more true in his day and age than it is now, given that he wrote it in 1843. So even before the failed revolutions of 1848/49.

But in the case of the Russian Bolshevist leaders it's up for debate. We're talking about only two persons after all. Lenin and Stalin. And of course their advisors and helpers. In Lenin's case Marx might have had more of an influence on how he designed the Soviet Union. But Stalin was different. He was more of a power player in his own interest. There's an excellent book by Simon Sebag Montefiore on Stalin's rule. Stalin: The Court of the Red Tsar. Montefiore spent his whole professional career studying Russia and the Soviets and published numerous books on the country and it's most prominent leaders. It's worth reading for everyone wanting to learn more on the details, since Montefiore was one of the first historians to get access to Russian archieves after the Soviet Union broke apart.