This is rank nonsense.
First, the Third Reich and Italian Fascism took root for two chief reasons. One, because the leaders capitalized on dire economic conditions and promised economic prosperity. Two, because the leaders concealed their darker purposes and intentions until they were fully entrenched in power.
Second, contrary to your claim, it was the religious who were the most vocal and vociferous opponents of the Third Reich, Mussolini and Soviet Communism -- and they suffered for their opposition. Second to the 6,000,000 Jews who died in concentration, Catholics were targeted by the Nazis for their opposition to Third Reich and their support of Jews, and Catholics were the second most frequent victims of the Holocaust. And they were specifically targeted for their opposition of the Third Reich and their support of the Jews in Europe.
And just who were the tens of millions of people send to the gulags by Stalin? They were the Russian Orthodox who refused to accede to the demand of state-mandated atheism. The price they paid for their opposition to the "humanist" government was a one-way ticket to a gulag, where they were intentionally starved to death (under the weak claim that there was a famine).
So, in fact, it was the religious of Germany, Italy, and Russia that defied the governments of those nations. The argument that it was the strong religious tradition of those countries which made these "humanist" monstrosities holds no water and has no historical support. In fact, it is a "blame the victim" argument.
BTW, if you want to see the most articulate statement of "secular humanism," you should read the Soviet Constitution.
Bullshit. A populace
dog trained to believe and worship nonsence is fertile ground for dictators, tyrants and utopian schemes - that's why we witnessed the birth of the most oppressive tyrannies in the most religious nations. History is replete with examples as it's been happening for several thousand years.
Another point you consistently fail to address is religion's impotence in stopping these brutal aberrations. One would think with all the promises of salvation, life everlasting and hope, and claims of moral and ethical superiority, people would not be so easily led astray or so willing to acquiesce to non christian authority. I know why you don't address it, we all do. You know in your heart moral systems that are not based on, or even eschew critical ethical inquiry like yours does, are doomed to fail when the shit hits the fan. A glaring contemporary example being the Catholic Church's breathtaking evil in dealing with the child molestation scandal. Orgs where self-preservation trumps sound ethical judgement are doomed to fail when people need them the most, like when the catholic church partnered with Hitler and signed the Concordat. Rather than having the courage and conviction to the do the tough but ethically right thing, they acquiesced thus legitimizing Hitler's regime for the world. The catholic church partnered with Hitler.
You also conveniently ignore the antisemitism. Hitler was able to parlay the hatred of Jews, fomented by christians/catholics for centuries, into the perfect smokescreen for atrocity.
Yeah, sure a few religious stood up to the tyranny, but it was too few and too late to stop the deaths of 65 million people. What ultimately stopped the madness was a governement based on secular humanist priciples and critical ethical inquiry - USA

.
Text book example of cowardice.