Shining Steel - Lawrence Watt-Evans - Bog

When John Mercy-of-Christ's soldiers ran up against weapons like none they had ever seen before, John's campaign to defeat the enemies of The True Word and Flesh came to a sudden halt. Once guns that could only come from Old Earth arrived, the doctrinal differences between his sect and the Chosen of the Holy Ghost had to be put to one side--for what other abominations might be in store?