“This is not a Republican Party anymore. It’s a cult,” former Republican Sen. Alan Simpson said last year. He was far from alone. Ever since Donald Trump blustered his way through the 2016 Republican primary and general election — trampling over long-cherished conservative principles, viciously mocking any less-than-perfectly-loyal party members and boasting he could commit murder in broad daylight without losing supporters — the Cult of Trump image has sullied the Grand...