Revival by Stephen King
The preacher starts messing with electricity. Fate deals him a rough blow and his fortune becomes tied with a small boy. Each travels through a few decades of America in the back half of last century. Their paths cross on occasion.
The preacher gets dangerous, becomes a demagogue and a revivalist. He cures people, but… They have unexpected side effects. Perhaps because they are ripping a tear in the warp and weave of things and starting to let in parts of the Great Old Ones? You’d have to read to find out.
This is King, so it’s a good yarn, loads of jus’ plain folks writing, and a whole lot of the author’s love of rock n’ roll and Americana.