[dugong]

I think that one of the most imaginative alternate history (+ time travel) plots using the Nazi theme was "The Proteus Operation" by James Hogan. The plot involves a timeline in which the world progresses peacefully and prosperously after World War I for several centuries. A group from the future of this timeline decides that history should have gone in a different direction. They go back in time to the 1920's and create disruption and disturbances and raise an obscure Austrian artist to power. Within 50 years, the Nazis have near total world domination and America is on the verge of falling. The American government sends a small group back in time to 1939 to try to stop the Nazis. (How they attained time travel technology is explained later). The group becomes marooned but attempts to complete the mission anyway. Among other things, they persuade Roosevelt and convince a failed British politician named Churchill to go back into government service. then history gets changed again.

An alternate history plot with a religious element is Mysterium, by Robert Charles Wilson. In this novel an accident in a government research facility throws a small Michigan town into a world where their part of North America is controlled by French speaking Gnostics. Their version of Gnostic Christianity in this world is particularly brutal and treats the hapless Michigan transplants as something malevolent that must be expunged.

Stephen Barnes wrote a series of novels in which an element of the plot was that when phone systems began using quantum technology, people would slip back and forth between timelines every time they used the phone. The result was increasing disputes about the facts of history. Sometimes I wonder if I’ve fallen into that kind of timeline recently.