In Mr. Trump, I see the worst and ugliest iteration of views I expressed for the better part of a decade. To be sure, I’ve had my share of controversy. On more than one occasion, I questioned Mr. Obama’s truthfulness about his religion. At times, I expressed hate for my political opponents. We now see where this can lead. There’s no place in our politics for personal attacks like that, and I regret making them.

I didn’t vote for Mr. Trump in 2016 because I liked him. I voted for him because he wasn’t Hillary Clinton. Once he was elected, I gave him a fair hearing, and tried to give him the benefit of the doubt. But I soon realized that I couldn’t support him because of the danger he poses to the country, especially the division he sows at every chance, culminating a few weeks ago in his ugly, racist attack on four minority congresswomen.

The fact is, Mr. Trump is a racial arsonist who encourages bigotry and xenophobia to rouse his base and advance his electoral prospects. In this, he inspires imitators.

Republicans should view Mr. Trump as the liability that he is: No matter his flag-hugging, or his military parades, he’s no patriot.