I’ve received tens of thousands of letters and other communications from Trump supporters the past few years, some of which have sparked extended dialogues. Two I got after last week’s column struck me as pertinent to this moment, and they make insufficiently appreciated points.

A gentleman of early middle age in Kansas City wrote to say he’d sat out the 2016 election because he was dissatisfied with both parties. But now he’s for Donald Trump, and the reason “runs deeper than politics.”

America’s...