I really enjoyed Michael Gaddis's There Is No Crime for Those Who Have Christ: Religious Violence in the Roman Christian Empire (University of California, 2005). The distinction Gaddis draws between what he calls "moderate" and "extremist" violence (which I'd call "mainstream" and "marginal") makes sense of a lot of conflict in secular as well as religious environments.
After Teresa de Ávila's account of her childhood wish to run away and be beheaded by the Muslims, I think my favorite line in the book is a quotation from a fifth-century Nestorian monk named Barsauma: "I never killed any true bishop." When I quoted it to a coworker today, she misunderstood it at first, thinking that Barsauma had killed "self-proclaimed" bishops. His targets were properly ordained and appointed church figures; he went after them because they weren't true bishops by his standards, which of course he assumed to be God's standards. (According to a hagiographic life of this holy man produced in Syriac a century or so after his lifetime, monks under his command also attacked and killed Jews praying at the ruins of the Temple Mount in Jerusalem. No doubt he would have claimed, following Revelation 2.9, that they weren't true Jews. Attacks on synagogues, as well as "pagan" temples and Christian churches of competing factions, were part of the repertoire of holy violence in those days.) What constitutes a "true bishop" is a question of definition, relative to the standards of a given religious faction, and Gaddis does a fine job developing the implications of this.
While Barsauma went to lengths not many respectable Christians would accept today, his basic attitude toward moral standards is very much with us. As I thought about his witticism, I found myself remembering Jeremy Lin's plaintive wish to "play basketball my way -- which is God's way." He also told an interviewer that his dream had always been to jog down a basketball court in a goofy way after making a sweet shot during a game, and the documentary about him shows him doing just that: skipping along slack-jawed with his shoulders down, like a cartoon character. (You can get a glimpse of Lin living his dream at about 1:55 in this trailer for the film.) This routine seems a lot less cute to me when I consider that in Lin's mind, his god had intervened to enable him to do it. Children were starving, drones were wiping out wedding parties, but Jeremy Lin's dream took precedence over such trivialities. (Come to think of it, though, Lin's god wasn't going to do anything about those starving children anyway, so no harm, no foul.)
Or consider this meme:
With all due respect to Archbishop Tutu, his god's ways are not our ways, so his inability to imagine God saying such things reveals more about the limitations of his imagination than about the morals of his god. I find it doubly hard to credit Tutu's unbelief since the Christian Bible, which he must know pretty well, is full of Yahweh punishing people for the very kinds of things Tutu says he can't imagine him doing. Perhaps Tutu believes in the wrong god?