Turkey is at a pivotal point in its history following the failed coup attempt of July 15. President Recep Tayyip Erdogan, having survived the coup plot, won fresh legitimacy and gained a new ally: religious fervor in the streets. Mr. Erdogan can use this impetus either to become an executive-style president, or he can encourage the forces of religion to take over the country, crowning himself as an Islamic leader.

Though the incremental acquisition of power has been more his style in the past, the powerful eruption of Islamic support for him over the weekend may prove too tempting. This is Turkey’s Iran 1979 moment—will a brewing Islamic revolution overwhelm the forces of secularism?

As the coup plot was unfolding on Friday night, Mr. Erdogan appealed to religious sentiments in the country, rallying his supporters to launch a counter-coup. On his orders, calls for prayer were issued from Turkey’s over 80,000 mosques at 1:15 a.m.—not a time when people are supposed to be praying. The strategy worked, the call to prayer acted as a call to political action, and religious Turks took to the streets in defiance of the secularist military. Together with pro-government police forces, they overpowered the military’s botched effort.

Since July 15, pro-Erdogan sentiments in Turkey have been running high. Calls to prayer continue throughout the day (Islam requires only five calls to prayer at set times daily), reminding religious Turks of their political duty to stand with the president.

Mr. Erdogan, a politician with an Islamist pedigree, came to power in 2003 as prime minister and head of the ruling Justice and Development Party (AKP). At that time, he followed a policy of economic growth to build a support base. He also moved away from Islamist politics, instead embracing reform and seeking European Union membership.