Ultimately, improving material conditions for people is the solution. Christianity has never exactly been good, but the US and its goals have made it what it is today. An Evangelical who just loses their faith without building critical thinking skills won't have changed much at all

Evangelicals are moral nihilists, so flipping their Atheism switch per se only lets them be self-aware moral nihilists. On the bright side, it can make them less tedious to deal with by cutting down on reflexive, "I'm not actually a bad person!" disclaimers that they package with their bigotry