Sure, it’s just a speech. Words, following and preceding airstrikes. But as a speech, it was a stunning departure from the usual platitudes without a plan. The leader who didn’t have a strategy for dealing with Islamic State nihilists a few weeks ago just dropped an idea bomb on the rest of the world. The “Muslim” president — a falsehood still held by nearly 25 percent of Republican voters — gave the Muslim world a blueprint for saving itself.

Until this week, most Western leaders have been afraid to say what Obama said at the United Nations. Sunnis dominate Islam, a religion of 1.6 billion people. The worst terror in the world today is being waged on behalf of a small, violent cult of death that is nominally Sunni. By enlisting at least five Sunni-majority nations in his campaign against the Islamic State, also known as ISIS or ISIL, Obama has taken the first step to get Islam to do what it must do. (It would help to have Turkey, the only Muslim nation in the North Atlantic Treaty Organization, and a Sunni-majority country, fully aboard with the 50 countries in the campaign to quash ISIS.)

“No god condones this terror,” Obama said. “No grievance justifies these actions. There can be no reasoning — no negotiation — with this brand of evil.” There again, his language was unvarnished, without filter or diplomatic dither.

Many in Obama’s own party heard only the echoes of George W. Bush. “Evil-doers,” coming from Bush, was a punch line. Cue up Will Ferrell and Jon Stewart. O.K., parallels granted. But Bush’s war in Iraq was nation-toppling born of hubris, followed by nation-building born of ignorance. Obama’s direct action against ISIS is designed to keep entire communities of “infidels” from being slaughtered by a cult under a black flag. His actions will save Muslims, the primary victims of Middle East terrorism, from other Muslims. It’s also in America’s interest, for those isolationists who think we should never try to stop overseas massacres on our watch.

Obama, the peace prize winner, is the only person who could rally the civilized world against a caliphate of violence. Who else would do it? The pathetic, hapless and corrupt Iraqi Army, built with American tax dollars? The United Nations? The Kurds? They will fight, but only for their interests and their territory.