There is no stretch there. It is completely logical. The people can't serve two masters who want their complete devotion. The ideologies are going to duke it out...no way around it. Even though Jehovah's Witnesses were a small group their intransigence greatly irked the Nazis and many were sent to the concentration camps.
https://en.wikipedia.org/wiki/Persecution_of_Jehovah's_Witnesses_in_Nazi_Germany
In a (proper) democracy the government is not totalitarian so it is willing to leave space for religious observance provided that this does not become a threat to the smooth running of the state. Not sure how the fact that totalitarian regimes may have persecuted gay people has any bearing on this point.
I'm saying that a group (religious or otherwise) doesn't have to be particularly totalitarian in order to earn the ire of a totalitarian regime. I am referring back to bonesmccoy's point:
The 20th Century had a couple murderous (to a degree I don't think we can still yet appreciate) ideologies that were inimical toward religion.
You've said that two competing totalitarian ideologies will lead to conflict. That is a fair point. But religious groups can be (and have been) just as easily targeted for xenophobic persecution as anyone else. That cannot always be ascribed to a confict between two totalitarian ideologies.
In other words, when it comes to totalitarianism and ideology, it doesn't really take two to tango. That's why I mentioned persecution of gay people. I'd also count Jewish people in this, though I see they were excluded in your original post. They weren't persecuted because of competing totalitarian ideologies; they were persecuted because the Nazis were totalitarian and they were Jewish (or gay). The conflict doesn't have to arise due to some kind of ideological competition.
edit: Coming back to this now that I'm back at my desk -
bonesmccoy claimed that religious persecution was a feature of several regimes throughout the last century. Your response that this persecution arose from a conflict between two competing totalitarian ideologies: that of the faith, and that of the state. My point is that that statement isn't really true, and is actually more than a little unfair: People were persecuted on mere suspicion of adherence to a particular religion, or association with such individuals, when it served the aims of the State.
Christians in particular lionize martyrs for "keeping the faith" under pressure and refusing to recant, and depending on your definition of “totalitarian” you could describe that as a totalitarian impulse. But religious people have also been persecuted simply because they held beliefs that violated a particular state policy, and they have been persecuted because they held beliefs at all. For example: the
Soviets were happy to co-opt religious fervor when need be – particularly during the Operation
Barbarossa. But at other times, Christians were thrown in prison for leading churches in their homes, due to violating
policies designed to eliminate religion from public and private life. Was that persecution due to a “conflict” between the totalitarian aspects of their faith and the wider community? Or is it simply the same xenophobic, paranoid persecution which happens to be a consistent feature of life in a totalitarian state? I would argue that it's the firmly latter.
So yes: I still maintain that it is a stretch to ascribe persecution of Abrahamic religious groups solely to a struggle between competing totalitarian ideologies. It comes off as a basic attempt to blame the most illiberal parts of religious belief for its marginalization in totalitarian regimes.
