CAIRO — Inside Al Azhar Mosque, a 1,000-year-old center of religious learning, the preacher was railing on Friday against Jews. Outside were rows of riot police officers backed by water cannons and dozens of plainclothes officers, there to prevent worshipers from charging into the street to protest against the war in Gaza.

“Muslim brothers,” said the government-appointed preacher, Sheik Eid Abdel Hamid Youssef, “God has inflicted the Muslim nation with a people whom God has become angry at and whom he cursed so he made monkeys and pigs out of them. They killed prophets and messengers and sowed corruption on Earth. They are the most evil on Earth.”

As the war in Gaza burned through its 14th day, Arab governments have felt their legitimacy challenged with an uncommon virulence. With each passing day, and each Palestinian death, the popularity of Hamas and other radical movements has ratcheted higher on the Arab street, while the standing of Arab leaders has suffered.

Nowhere in the Arab world is the gap between the street and the government so wide as here in Egypt, which has a peace treaty with Israel and has refused to allow free passage of goods and people through its border with Gaza, a decision that has been attacked by Islamic and Arab leaders and proved deeply troubling to many Egyptians. And so the government of President Hosni Mubarak appeared to lean back on its standard formula for preserving authority at Friday Prayer, relying on its security forces to keep calm on the street and government religious institutions like Al Azhar to try to appease public sentiment, in this case by lashing out at the Jews in response to Gaza.

“The pressure is mounting on Egypt,” said Abdel Raouf el-Reedy, a former Egyptian ambassador to the United States. “How come you keep the Israeli ambassador here? How come you keep the Egyptian ambassador in Israel? How come you still export gas to Israel in spite of a court order to stop? The system is on the defensive. Public opinion is more clearly on the side of Hamas.”

The mood on the streets of Cairo feels somber, dark, dejected. There is a heavy security presence. Armed riot police officers are massed outside of professional organizations, like the Doctor’s Syndicate, that are often run by members aligned with the Muslim Brotherhood, the officially outlawed but tolerated Islamic movement. Massive troop carriers clog small side streets.

Over three days of interviews here, people seemed deflated about the public criticism their country had received, let down by the failure of their own government to help the Palestinians and sickened by the deaths of hundreds of Palestinians, not only combatants but many women and children as well. Over and over, Egyptians said they felt the only ones they could trust were the Islamists — not their government.

“The Muslim Brotherhood’s work gives them credibility,” said Heba Omar, 27, who collected about $4,000 from her neighbors to donate to a charity controlled by brotherhood members. “They do what they can do at times of crisis.”

On Thursday, three young men looked over the railing at the choppy gray waters of the Nile, schoolbooks tucked beneath their arms, jackets zipped up to their chins against the winter chill. “Of course we are sad,” Muhammad Atef, said in a low, defeated voice. “There is nothing we can do. There is nothing in our hands.”

Mr. Atef and his schoolmates, Hazem Khaled and Ramy Morsy, all 19 years old and studying to be electricians, were walking along the Nile Corniche, just opposite the imposing office tower that houses Egypt’s Foreign Ministry.

The diplomats handling the crisis were out of town, in New York City at the United Nations. But the young men said they were looking elsewhere for a chance to help the Palestinians. “The Islamists are very close to us,” Mr. Atef said.

“They are people we can trust,” Mr. Khaled said.

“We trust Islamist organizations,” Mr. Morsy said.

Talk like this has helped press Egypt to change its approach to Gaza, if not its actual policies. When the war first began, Foreign Minister Ahmed Aboul Gheit lashed out at Hamas, blaming it for inciting the violence by refusing to heed Israel’s warnings to stop its rocket fire.

Egypt took a similar position in 2006, blaming Hezbollah for provoking Israel and setting off its bombing campaign against Lebanon by grabbing two Israeli soldiers in 2006. But then, as now, the government quickly changed its posture in the face of public outrage. “Mubarak lost credibility, not just in the Arab world but in Egypt, too,” said Fahmy Howeidy, an Egyptian writer with Islamist sympathies whose work used to appear in the main government-controlled daily newspaper, Al Ahram.

Egypt quickly tried to recover its standing by promoting a cease-fire initiative. That failed, and again the pressure has been growing. Political and diplomatic experts here say that officials are hoping to prop up Fatah, the secular Palestinian faction that was routed by Hamas and now is in charge of the West Bank. But they fear that as the fighting goes on, their reluctance to come to the aid of Hamas will accomplish exactly the opposite. Fatah may be undermined and Hamas empowered.

“I don’t think that Fatah will be able to go back into Gaza,” said Mr. Reedy. “This is the irony of Israel’s military strength. They will not eliminate Hamas. Hamas will live in the minds of the people.”

For average people, the concerns of the state pale in comparison to the desire to help stop the bloodshed. At Friday Prayer, which serves as a nexus between religion and politics for Muslims, leading Islamic scholars in the Middle East called for Muslims throughout the world to come together under the flag of Islam to help. And preachers heeded their call, very often taking aim at Israel, the Jewish people, the United States and the Egyptian president.

“The truth about Jews is that they killed prophets and messengers and broke pacts and promises between them and other nations,” said Ilyas Ait Siarabi during his sermon in a neighborhood mosque in Algiers. “And they seek to spill blood and kill the souls of innocent old men, women and weak children.”

At the state-controlled Al Azhar in Cairo, Sheik Yousef ended his talk by calling for unity. “Muslim brothers, division among Muslims today is what weakens them and made the enemy get at them,” he said, his voice booming from loudspeakers mounted outside the mosque. “What we have to do, Muslim brothers, is come together and strengthen our external and internal fronts.”

Before the service had started, a woman had stood in front of the women’s section — men and women pray in separate areas of the mosque — and asked everyone to stay behind when it was over. She said they wanted the women to create a wall to protect the men, who planned to protest, from being taken or beaten by the police. When the service was over, a woman jumped to her feet and shouted, “Open the border, open the border.”

A police officer shouted for everyone to leave, and the congregants made their way onto the street crowded with security men and riot police officers. There never was a demonstration.