This list is incomplete; you can help by adding missing items. (November 2012)
The Terra Incognita fantasy series by Kevin J. Anderson depicts two opposing religions going into an all-out religious war, fiercely contending for possession of a Holy City which is sacred to both (loosely modeled on the confrontation between Christianity and Islam over Jerusalem, during the Crusades). The followers of the two religions whip each other into a genocidal fury by an ever-escalating spiral of massacres and counter-massacres, atrocities and counter-atrocities. But finally, the God in which both of them profess to believe puts an end to the bloodshed by showing up in person at the middle of a battlefield and issuing a stern warning – unless they immediately stop killing each other in His name, he would consider wiping out all of them and starting a new Creation from scratch. The reader is shown that in fact, God was too tender-hearted to actually carry out this threat. But the humans who heard Him could not be sure of that, and they are intimidated into making peace, with their respective priesthoods dropping fanaticism and embarking on an ecumenical course.