Mr. Trump rightly sees an ideological war being waged against the West by a hateful, millenarian obsession targeting core American constitutional and philosophical principles. From that assessment flow several policy consequences, most important the imperative to destroy the terrorist threat rapidly and comprehensively before it kills and maims more innocent people. Mr. Trump correctly argues that, in combating Islamic State, al Qaeda and others, “we must use ideological warfare” as well as stronger military and intelligence operations, and be “a friend to all moderate Muslim reformers.” This strategy is entirely consistent with what Jordan’s King Abdullah II and other Arab leaders characterize as a civil war within Islam.

In contrast, Mr. Obama and Mrs. Clinton still believe terrorism is a law-enforcement issue. They fail to grasp the ideological war we are in and therefore refuse to combat the enemy effectively. There were once those who did not see Communism as an ideological threat. They played down their views publicly because U.S. public opinion was overwhelmingly contrary, as Mrs. Clinton and Mr. Obama are doing now regarding terrorism. Mr. Trump should emphatically move the debate about radical Islam into the campaign spotlight. Let’s see who stands where.

Mr. Trump’s speech also demonstrated his willingness to face the hand dealt an incoming president, rather than following ideological abstractions, as Mr. Obama has consistently done.