[quote=Magic Magnum]
1. Yes, but we ain't psychic. If someone comes up and says "I am doing this cause of God!" we can safely assume they are doing it because of God. In the same way that someone went "I am doing this because there is no God!" we can assume that's their reason. Except no one had said this, you are suggesting hidden motivations. Which although very plausible (if not most likely, everyone will have some motivations they keep to themselves) you are at no position or ability to judge or determine them. Is it theoretically possible for an atheist to start a violent purge of religious people because they are religious? Sure, humanity produces some very messed up people. But do we have any recorded cases (Not assumed from an absence of religion motivation) of that being the motivation? Nope.2. More precisely, killed because they worshipped/believed something that wasn't there leader. They could have gone around worshipping their local baker and they'd still get killed. It was about praising something other than their leader, not about the fact they were religious.3. Yea, I would. Because it proves itself to have religious motivations, but it doesn't so it's not a religion. In the same way that if I happened to believe in God that would make me religious. That's not a double standard, that's just fact. Belief/worship of a God is religion.
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1. Let me posit an alternate explanation.

Raw, unadulterated military predation has been, up until recently, perfectly acceptable. The Romans killed you and took your stuff without any qualm nor issue. Barbarian tribes across Europe quibbled with and slaughtered each other. Genghis Khan. The Persians in Greece, Alexander in Persia and India. The Vikings raided with no aims to spread their faith.

Enter Christianity to Europe, whose prime teacher is Jesus Christ and whose Council of Jerusalem nullifies the argument you are indubitably about to make with the OT. Christ preaches nonviolence, and loving thy neighbor. While predation does not end, it now has to resolve the cognitive dissonance certainly in the minds of rulers and soldiers, Christianity's adherents, on the contrast between this predation and their religion. Get the Pope to sanction it, (Crusades and Norman Invasion), claim the guys whose stuff you want is perverting the faith or you have rights to his land, whatever. You had to have SOME form of justification. Rather than SPARK conflict, religion helped neutralize it. 

2. So religion is by and large a bulwark against totalitarianism? Glowing endorsemen by Mao and Stalin, that they felt thr religious a threat to their rule.

3. Just as saying "There is no God" is Atheistic. If "You die for Christianity!" Is killing for religion, "You die for Communism!" Is killing for Atheism.