Depends on how broadly you define "religious war."
I'm sure people who were conquered and enslaved in the name of a god-emperor of Rome or a Pharoah weren't much happier about it than they would have been if it had been in the name of some invisible being.
For the most part, "religious" wars have been wars for normal reasons with religion used to dress up the motivations. There have been exceptions, with true fanatical motives, but I think they are the exceptions.
As far as alien versions of Christ, C. S. Lewis' space triliogy postulated that Earth was the only planet that NEEDED divine saving.