Before the vote, Essam el-Erian, a Brotherhood leader and spokesman, appeared on a popular television show, “The Reality,” arguing for the government’s position in favor of the proposal. With a record turnout, the vote was hailed as a success. But the “yes” campaign was based largely on a religious appeal: voters were warned that if they did not approve the amendments, Egypt would become a secular state.

“The problem is that our country will be without a religion,” read a flier distributed in Cairo by a group calling itself the Egyptian Revolution Society. “This means that the call to the prayer will not be heard anymore like in the case of Switzerland, women will be banned from wearing the hijab like in the case of France,” it said, referring to the Muslim head scarf. “And there will be laws that allow men to get married to men and women to get married to women like in the case of America.”

A banner hung by the Muslim Brotherhood in a square in Alexandria instructed voters that it was their “religious duty” to vote “yes” on the amendments.

In the end, 77.2 percent of those who voted said yes.

This is not to say that the Brotherhood is intent on establishing an Islamic state. From the first days of the protests, Brotherhood leaders proclaimed their dedication to religious tolerance and a democratic and pluralist form of government. They said they would not offer a candidate for president, that they would contest only a bit more than a third of the total seats in Parliament, and that Coptic Christians and women would be welcomed into the political party affiliated with the movement.

None of that has changed, Mr. Erian, the spokesman, said in an interview. “We are keen to spread our ideas and our values,” he said. “We are not keen for power.”

He would not comment on whether the Brotherhood had an arrangement with the military, but he said the will of the people to shift toward Islam spoke for itself and was a sign of Egypt’s emerging democratic values. “Don’t trust the intellectuals, liberals and secularists,” Mr. Erian said. “They are a minor group crying all the time. If they don’t work hard, they have no future.”

But the more secular forces say that what they need is time.

“I worry about going too fast towards elections, that the parties are still weak,” said Nabil Ahmed Helmy, former dean of the Zagazig law school and a member of the National Council for Human Rights. “The only thing left right now is the Muslim Brotherhood. I do think that people are trying to take over the revolution.”