ISPARTA, Turkey — After retaking Taksim Square in Istanbul after hours of ugly street battles with police officers firing tear gas this month, many of the haggard protesters cracked bottles of Efes beer and raised them in a mock toast to their prime minister, who had recently pushed through a law to curb drinking.

And even in Isparta, a religiously conservative region that is a wellspring of support for Prime Minister Recep Tayyip Erdogan, a small group of residents, drinks in hand, gathered outside the office of the local governor who is an ally of the embattled prime minister and chanted, “Cheers, Tayyip!”

Drinking is far from the only issue held up in the intense antigovernment protests that have convulsed Turkey for more than a week. But it has become closely intertwined with the broader complaints of demonstrators fighting what they see as the rising authoritarianism of the Turkish government.

It also cuts to the heart of Turkish identity, as both sides have cast it as a clash of Islamic and secular values. While protesters have held up new limits on drinking as an affront to the secular values of modern Turkey, Mr. Erdogan has said that “religion demands” curbs on drinking. He has gone so far as to implicitly refer to Mustafa Kemal Ataturk, the founder of Turkey and a notoriously heavy drinker, as a “drunkard,” and in one of a series of speeches he delivered Sunday to cheering supporters, accused protesters of taking beer into mosques.