Newbies Beware...

[Saber Cherry]

There are only 2 possiblities. First, you had "Dominion Strength" as the victory condition. Second - and more likely - there was a game bug, and you should post it in the bugs thread and send your Last trn file to Illwinter.

You do not lose from dominion unless you have zero dominion on the entire map - no white candles anywhere - which was not the case.

Priests and temples are not important. You can always appoint a prophet, summon a holy/unholy unit, seduce one, mind-control one, get one randomly by luck, discover a site which gives a temple, get a temple by luck, or whatever... there is never an insurmountable barrier to getting holy units again after losing all of them, mainly because you can always have a prophet... though there is a several-turn wait after the old one dies.