An oil crash and some sort of massive church scandal that causes people to leave Evangelical Protestantism en masse, in rapid succession.
Impossible. The whole thing about being an evangelical protestant is that even if your church is torn apart by scandal or schism, you can just go to another one. Not lose your religion entirely. It’s not like the Catholic Church where it’s all centralized; the pastor of every church is like their own Pope basically. And even then, not like the RCC suffered too badly from their own massive scandal. There is no conceivable way to rapidly get all these people to just totally abandon evangelical Christianity, and even if they did, that still wouldn’t guarantee they’d suddenly become socially liberal Democratic voters. Religion in general is on the decline in this country, and that generational change is what might ultimately liberalize some places over time, but it’s happening slower in states like Oklahoma than others. I’d imagine it would be one of the very last holdout states with a strong evangelical presence, in fact.
Oh and the other thing about evangelical Christianity is that it strongly encourages “evangelism,” i.e. converting people. So that’s another reason why it’s declining slower than mainline Protestantism and Catholicism in the US. Even the people they lose can be replaced with new converts, while those churches don’t put nearly as much emphasis on converting people and thus have older populations that are dying out faster. Plus they are less zealous/conservative as it is.
