A lot of US protestant theology is rooted in a concept called "dispensationalism" that was introduced in the mid 1800s. It's a heady concept to explain, but essentially it comes down to a few linked core concepts:
- The secret, sudden arrival of Jesus to "rapture" believers away
- The world is getting worse, not better. There is limited use in improving society.
- Strict literalist interpretation of all scripture (where convenient, obv)
- An individual's ability to discern scripture as well as the state of the world
- Obsession with Israel as a nation-state
https://christianhistoryinstitute.org/magazine/article/dispe...
By tracking this number, you have a good proxy for the current fervor of a lot of intertwined political concepts in the US.