The Templar are very, very devout followers of Kalian Broodikus
They don't use White-Crosses, but they are the equivalent to the Knight-Templar (although to a much more extreme level). And Templar may have women and often do live in grand castles.
If anyone has played Diablo II, a lot of my inspiration for this entire story came from the Zakarum (the corrupted order of paladins, by Mephisto, Lord of Hate).