MTH,
It seems you might be on the verge of understanding that the atrocities committed under Stalin were committed because he and his minions were vicious, deluded, sociopaths acting on a non-evidence based ideology which for the sake of simplicity, we can call communism.
Suppression of religion was
one aspect among many of their ideology, driven in part because the Russian church was part of the old power structure that Lenin and Stalin wanted to destroy.
Of course, had they been believers in the Christian deity, they would have seen things differently, but to say that there is a direct connection between any of the communist theorists or dictators' disbelief in the Christian deity and the horrors eventually perpetrated by the lunatic Stalin is nothing more than delusional and wishful thinking on the part of Christians who want so very, very, badly to think atheists in general must be awful people.
Conversely, was Christian theology just
one aspect among many of the motivations of those who burned witches in Salem or Europe, or of the Crusaders, or of the people who burned William Tyndale and who dug up

and burned John Wycliffe's bones, men whose crimes were heresy - that is, translating the Bible into English, for but a few examples? (Of course, William and John were only
two men - one shouldn't make too much of it, right?)
Or was Christian theology just a wee bit more central to those wonderful activities?
And how about today's Muslim suicide bombers? Do you think the idea that they're going to heaven, to be joined later by their families, might be kinda central to their willingness to disintegrate themselves and anyone else who might be nearby, or do you buy the argument that it's really all just about "politics?" Their theism is just peripheral, right?
I'm not surprised, frankly, that you would buy into the Stalin/atheist/death camp notion, given that you also buy the idea that the Inquisitions were really "not so bad," and that the Inquisitors were really just seeking to keep people
falsely 
accused of heresy from being harmed by
other crazed believers. Just keeping order, were they? Why, yes, they must have been fine gentlemen. And surely the stretching racks and waterboarding tables and whips and knives and needles were all necessary to keep those unruly peasants in line, no?
You know, the Catholic church (I forgot, are you Catholic?) has a very, very, large vested interest in putting a gloss on things like the Inquisition, the murder of Hypatia, the trials and oppression of Galileo, the burning of Tyndale and of Wycliffe's corpse, the molestation of children world-wide, etc., etc., etc.
I'll bet you can find some truly AMAZING scholarship at Notre Dame that explains away all of these things, blaming them on atheists or protestants or perhaps shortages of incense and crackers.
It looks to me like you, Catholic or not, might find such scholarship more persuasive than many of the rest of us, believers or atheists.
OK, I've got to check out of here for a month or so. The holidays, finally selling a house

and moving, and work will keep me scrambling for a while.
Happy holidays, and yes, very much including merry Christmas, to all!
Those who know the most of nature believe the least about theology. - Robert Ingersoll