As the 25th anniversary of 9/11 approaches, Americans who remember that day also remember its aftermath.

Along with the shock, horror, suffering and death, there was resolve: We would never forget what happened. And we would never let it happen again.

Thankfully, nothing on that scale has happened since.

But too many Americans seem less alert to the threat of radical Islamism.

A for-profit sharia finance industry operates across America. A North Texas school was established and staffed by relatives of convicted Hamas operatives. And New York’s current mayor has been photographed with an unindicted co-conspirator in the 1993 World Trade Center bombing.

For those of us who remember the terror of 9/11, these developments are almost unbelievable. And they’re frightening.

Because we know what happens when people forget the past. They risk repeating it.