the vast majority of Purity First and their ilk would be religious fundamentalists
Disagreed. They made it about money, and it's fine. Yes, you'd have plenty of religious nutbags going insane, but you'd also have plenty of labor types doing the same. The rich could spend tens of thousands on augs and make themselves more than human while the other 99% of the world would go from being barely able to compete to entirely unable. It would end upward mobility.