CAIRO -- Muslim clerics urged worshippers to vote "yes," while thousands of supporters and opponents of a controversial draft constitution filled the streets of Cairo on Friday in dueling protests on the eve of a referendum on the charter that has left the country deeply polarized.

The draft has pitted Egypt's newly empowered Islamists against the country's mainly secular liberals, minorities such as Christians and a large sector of moderate Muslims. Liberal and secular activists charge that it opens the door to rights abuses and Islamist domination.

Both sides stepped up their campaign in favor and against the constitution after weeks of violence and harsh divisions that have turned Saturday's vote into a stark choice on whether Egypt takes a major step toward theocratic rule after the rise to power of the fundamentalist Muslim Brotherhood.

Religious authorities had issued orders that mosques should not be used to manipulate the vote, but several clerics, especially in conservative southern areas, took to the pulpit to tell their congregations that voting in favor of the constitution is seeking victory for Islam.

"Voting yes is like jihad for the sake of god," Sheik Abdel-Akher Hamad told worshippers in the southern city of Assuit. "It preserves Egypt from evils and from those who want to sabotage Islam and Muslims."

The crisis, which began Nov. 22 when President Mohammed Morsi, who is backed by the Brotherhood, issued decrees, since rescinded, giving himself and an Islamist-led constitutional assembly immunity from judicial oversight so the draft charter could be finalized before an expected court ruling dissolving the assembly.

Morsi, who took office in June after a narrow victory in the country's first free elections, joined weekly Friday prayers at the el-Farouk mosque near his house in northern Cairo and left without giving a speech.

The cleric at his mosque remained neutral.

"Those who think that rejecting or approving the constitution is the path to heaven or hell is mistaken," he said, referring to a slogan constitution supporters have used. "No one rules whether someone goes to heaven or hell but God almighty."

But in many ways, the pros and cons of the draft constitution have been overshadowed by the worst crisis to hit Egypt since the overthrow nearly two years ago of Hosni Mubarak's authoritarian regime. With killings and mass street protests defining the past three weeks, newspaper and TV commentators have warned of a country moving toward civil strife and a schism that may not be bridged.

The crisis also has united the long fractured opposition, which had considered boycotting the referendum but instead officially launched a campaign Thursday calling on voters to go to the polls and reject it.

Mostly liberal and secular protesters opposed to the charter marched on the presidential palace Friday chanting against what they called "the Brotherhood constitution."

The densely written document was passed by an 85-member constituent assembly composed of mostly Islamists earlier this month. Morsi rushed it to a vote scheduled for the next two Saturdays.

Earlier, liberals and church representatives withdrew from the panel drafting the charter, protesting the efforts of its Islamists to pass articles and embed others with clauses they feared could usher in a theocracy.

The opposition took out advertisements in newspapers and on television detailing their arguments against the charter. The Morsi camp's message was far simpler. A "Yes" to the constitution is a yes to Islam.

Sheik Mohammed Sayyed, affiliated with the Muslim Brotherhood, put it bluntly during prayers at the el-Helali mosque elsewhere in Assuit. "Tomorrow is the day we will seek victory of Islam," he said.

"The first phase of implementing Shariah (Islamic law) is the election of a Muslim president. The second phase is to hold referendum on the constitution," he said, urging voters to go to the polls in groups. "Those calling themselves liberals and salvation of Egypt, are saboteurs who sabotage Egypt."