Maybe easier, yes, but I'm talking about justification. Regardless, I think it is relatively easy for someone to act selflessly. The good you do is humanly evident, and your moral conscious easily regards that as good behavior. Do churches do a lot of good? Yes. But you should thank people, not religion, for that good they do.

But, it becomes a lot easier to pick up a gun and shot someone dead if you believe your God (whichever God is convenient to believe in) wants you to do it. It's easier to sacrifice yourself for war if you believe a heaven is waiting for you. Its easier to condemn gays if you think your bible wants you to, and religious faith makes it simpler to deny scientific fact.

Oh and about WW2 era dictatorships:

In a 1922 speech he[Hitler] said,"My feelings as a Christian points me to my Lord and Savior as a fighter [...] who [...] recognized these Jews for what they were and summoned men to fight against them..." In a 1928 speech, he said: "We tolerate no one in our ranks who attacks the ideas of Christianity ... in fact our movement is Christian." Given his hostility to Christianity, Laurence Rees wrote that "The most persuasive explanation of these statements is that Hitler, as a politician, simply recognised the practical reality of the world he inhabited... Had Hitler distanced himself or his movement too much from Christianity, it is all but impossible to see how he could ever have been successful in a free election". Alan Bullock wrote that even though Hitler frequently employed the language of "divine providence" in defence of his own myth, he ultimately shared with the Soviet dictator Joseph Stalin a materialistic outlook "based on the nineteenth century rationalists' certainty that the progress of science would destroy all myths and had already proved Christian doctrine to be an absurdity". According to Geoffrey Blainey, when the Nazis became the main opponent of Communism in Germany, Hitler saw Christianity as a temporary ally. He made various public comments against "bolshevistic" atheist movements, and in favor of so-called "positive Christianity"

Regardless, every WW2 era relied upon nationalism, which in it's extreme forms resembles religion.

I've never heard of a story where a country wages war because theres no heaven and no god and since humans are just organic blobs of carbon based molecules its okay to kill them.

The idea that if hitler was religious he wouldn't have killed people is absurd.