You're right about the etymology of "Inquisitor" and "Crusader", but when I first wrote these down I figured that they'd appeared in enough generic fantasy that they'd become a bit distant from their Christian origins. On second thoughts, and considering your comment, a lot of people might not see that distance...they might get a bit of a disconnect between these roles and the remainder of the setting.
I'm now thinking of shifting the Hunter-Disciple dual-class to "Avenger", and the Warrior-Disciple dual class to "Zealot" (I considered "Exalted", but didn't want any issues with people drawing connections to other RPGs...I also considered "Dervish", but that links pretty strongly to another religion). These two terms should be more religiously neutral.
The Warrior-Adept dual-class will probably become the "Raider".
A few reads through the text have shown me a couple of very confusing aspects, so I've made a few changes. These are mostly regarding the way voidstones expel energy and degrade over time...but I've also developed a completely different system for experience and heroic development.