People are inherently violent, and will always find excuses to start war's regardless of their religious affiliation. Most of the modern wars/battles have been fought for natural resources and political domination, two ideas that are quite secular. So, pretty much everything leads to war, that isn't a knock on religion or secularism.
It is fact that most of the modern wars have been fought for Material gains. This is irrefutable fact and cannot be refuted by secularists blaming alone those who fought these wars as our fellows secularists here disagreeing with this question are propagating. Secularism is indeed not the way forward for humanity!!
I asked this question as a response to what I have perceived as a common theme in peoples oppinions on this site. People seem to love to argue that atheist leaders are responsible for more deaths than religious wars and that somehow that means atheism leads to war which I think is flat out not true. Its similar to how some people confuse the fact that someone believes the diversity of modern life came from Darwinism with people believing that social Darwinism is a valid option for how we treat our fellow man.
People like to say "Most of the wars were actually fought for secular reasons." What does that mean? Somehow a war that is fought for any reason other than God is a point against atheism? No I dont agree with that. Hitler killed Jews because he was a power hungry rascist not because they believed in God and he didnt. I will be the first person to admit to you that most of the wars that are commonly attributed to just religion have a quagmire of different factors that caused them but saying that atrocities commited by atheists have something to do with their lack of belief in God is just untrue.
There is no evidence that secularism leads to war. In fact, most religious have been implicated in wars in the past. It is likely that secularism might prevent wars. Most pacifists do not subscribe to a particular religion, and even if they are religious, they agree to work with people of other religions to solve their problems.
There can be no reasonable argument that demonstrates that without religion, a community (nation, region etc.) devolves into anarchy and war.
The argument against this is most likely that withdrawing religion also removes a society's religious values but as these are merely a decent moral code, if society were to maintain its moral code without the presence of organized religion (which, even without religion ever have being invented, societies would still have invented a moral code) then there would be no reason society would automatically devolve into fighting