"Evangelical" was a term adopted by fundies as a marketing strategy, since "Fundamentalism" wasn't packing them in. But it's an anti-intellectual, populist movement that says you don't have to learn from stuffy, effete committees of seminary graduates to understand the Bible. This appealed to...
I found this interesting take on the origins of evangelicalism. medium.com/love-thy-nei...
...men who had lost their sense of what it means to be a man during the Industrial Revolution. Brawn was becoming redundant, and engineers and other pencil pushers were providing for their families better. Pile that on top of the emasculation of who instructed them Sundays on right and wrong...
...and populist think-with-your-gut evangelism seemed quite appealing by comparison. The committees would have to rope in the wayward every ten years or so. You can see such taking the evangelists to task by those who actually knew the Bible in "Elmer Gantry" -- a pretty important work.