Turkey was supposed to be the stable, Muslim-majority democracy on which the United States could rely as a strategic partner in the Middle East. The demonstrations that rocked Turkey in June came as a surprise to many in the West, and the brutal repression of those protests shocked those who thought of Prime Minister Recep Tayyip Erdogan as a democratic reformer. With international media attention no longer focused on the streets of Istanbul, conventional wisdom holds that the crisis is over and order has been restored.

But this assessment is too sanguine. Erdogan is turning Turkey into a powder keg in an attempt to shore up his own political base. He is intentionally activating the longstanding fault lines separating religious and secular Turks — and most dangerously the divide between the country’s Sunni majority and its Alevi minority. If he continues to do so, Turkish democracy itself could become a casualty of his confrontational policies.

On Sept. 8, the police and Alevis clashed for a full day in an Ankara neighborhood. Alevis, a heterodox Muslim minority who make up between 15 and 20 percent of the Turkish population, have long suffered oppression and discrimination. Their faith and places of worship are not officially recognized, and Alevi children are denied exemption from Sunni religious education....