Karen Johnson went to her Lutheran church so regularly as a child that she won a perfect attendance award. As an adult, she taught Sunday school. But these days, Ms. Johnson, a 67-year-old counter attendant at a slot-machine parlor, no longer goes to church.

She still identifies as an evangelical Christian, but she doesn’t believe going to church is necessary to commune with God. “I have my own little thing with the Lord,” she says.

Ms. Johnson’s thing includes frequent prayer, she said, as well as podcasts and YouTube channels that discuss politics and “what’s going on in the world” from a right-wing, and sometimes Christian, worldview. No one plays a more central role in her perspective than Donald J. Trump, the man she believes can defeat the Democrats who, she is certain, are destroying the country and bound for hell.

“Trump is our David and our Goliath,” Ms. Johnson said recently as she waited outside a hotel in eastern Iowa to hear the former president speak.