Ryan Sayre Patrico, over at First Thoughts, has a typically ham-fisted response to a rather thoughtful piece by Laurie Fendrich at the Chronicle of Higher Education. She imagines a world where monotheism failed to take root, and he snarls back with a typical Christian response; such a world would be a living Hell because of the absence of the beneficent influence of Christianity, even attempting to make the point that the Peloponnesian War had a much higher death-rate than World War II. He fails to mention, of course, that the Peloponnesian War was not fought for religious reasons, but geopolitical ones. Athens wasn't attempting to impose its version of Hellenic Greek paganism on Sparta.
Ms. Fendrich's original point remains, however; polytheist societies are, as a rule, much more tolerant on a religious level than monotheist societies are, because implicit within polytheism is a certain tolerance of other beliefs. No one ever claimed pagans were free from war for other reasons, but knocking down that straw-man seems to compose the entirety of Mr. Patrico's argument.
The example of Pagan Rome's intermittent (and ultimately futile) repressions of early Christianity, of which commenter Mr. Mendez reminds us, is a special one; Rome was in fact noted for its tolerance of local cults and religious practices, even granting a special dispensation for the Jews from the requirement of Emperor-worship. The Christians ran afoul of them specifically because theirs was a new faith that sought to undermine the Roman faith; had Christianity been capable of co-existence with other religions (as did, for exmple, Mithraism, one of Christianity's chief rivals at the time), I think the Roman response to it would have been vastly different.
Oh, and his link is incorrect. It should point to the article I linked above.