The Shattered World
Immediately after The Shattering, the survivors turned upon the mages that had previously been seen as their most valuable assets. Fearing a repeat of that calamity, unruly mobs formed and descended upon the mages in their ritual circles. In the first moments after The Shattering, the mages, distracted by the calamity itself, were caught off-guard, and most were immediately caught and murdered.
What followed was roughly 50 years of paranoia, with fear-crazed lynch mobs seizing, torturing, and murdering anyone suspected of being a mage of any kind. What few mages survived were forced into hiding out of fear of being next; others continued to live within society, choosing instead to hide their abilities.
Naturally, not everyone who was accused — and subsequently put to death — was actually a mage, while at the same time some of the most prolific accusers were themselves mages, hoping that their apparent fervor in rooting out hidden mages would shield them from suspicion.
It wasn’t long, of course, before churches began to spring up, espousing the belief that the unruly mobs seizing and murdering accused mages were in fact doing the will of the gods, and The Purge was in fact a holy crusade with the goal of removing the blight that is magic from the world. The largest of these, the Church of the Holy Purity, rose quickly, even subsuming multiple smaller churches with similar goals, and even within many nations achieved significant political power. Paying homage to no particular deity, and playing directly into the fears the people had of magic and mages, Holy Purity was welcomed everywhere it went.