We tried to warn people — hipster friends, Republican neighbors, fellow suburban parents wrangling toddlers near the Thomas the Train section at Barnes & Noble. This was going to be a war on Islam. Not “radical Islam,” but Islam itself — which includes three million American Muslims and a global population of nearly 1.7 billion people.

The signs have been there for years, but many people said we were whining, exaggerating or claiming victimhood.

Even when Donald J. Trump said, “I think Islam hates us.” Just to make sure he wasn’t subtle, he also promised an extreme vetting of Muslims. He promised a ban on Muslims.

Still, people didn’t believe it was going to happen.

At the Democratic National Convention in Philadelphia, a Republican police officer laughed at my dark humor — I asked if he would bring me halal meat in the Muslim camps — and assured me I shouldn’t take Mr. Trump seriously. An elderly man in Maine, wearing his red cap, put his hand on my shoulder and promised me that after November I would understand how this once great country would be great again.