For decades, skeptics prevailed in the debate over whether Islam and democracy were compatible. But today, the two have become codependent.

Since October, Islamist parties in Egypt, Tunisia, and Morocco have won the right to form governments in free elections. They could score well at polls in Libya and Yemen—and maybe even Syria at some point. These six countries account for half the Arab world’s more than 300 million people, and their Islamist leaders are on a tear to prove their democratic bona fides. Egypt’s Muslim Brotherhood met U.S. officials in Cairo, then visited Washington. Tunisia’s new government hosted Hillary Clinton, while Morocco’s prime minister, hoping to lure foreign investment to his country, has urged cooperation with the United States. The new outreach has even included some unexpected Islamist vows to, say, honor international treaties (read: Camp David accords with Israel) and accommodate Western customs (read: alcohol and bikinis), in an effort to lure tourists back.

The trick for the U.S., of course, lies in deciphering who means what they say. Some 50 Islamist parties—excluding purely violent groups—now constitute a crowded political spectrum in the Middle East; formerly unimaginable alliances are suddenly unavoidable. This new cadre of nonviolent Islamists may be the most important partners Washington cultivates over the next decade.

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