Cairo (CNN) -- Tens of thousands of people demonstrated Friday in Tahrir Square, where they called for the implementation of Islamic law in Egypt.
The congregation brought together conservative Salafists as well as members of the Muslim Brotherhood and Islamic Jihad, who arrived in hundreds of buses from across Egypt.
The crowd delivered its message through signs, flags and chants: "Egypt will return to Islamic sharia law! Liberals and secularists are the enemies of Allah! The solution is Islam!"
Friday's shouts contrasted with the calls that emanated from the same location in February, when thousands of Egyptians took over Tahrir Square, demanding that the autocratic Hosni Mubarak step down and that free and fair elections be held. Islamist groups in Egypt have said they support democracy and elections, if only to use them as a means to achieve their goal -- via the ballot box -- of creating a religious state.
The Muslim Brotherhood, Egypt's largest opposition movement, was banned from politics under Mubarak's regime; Islamic Jihad, another banned group, says there is room in the new Egypt for their voices.
"All the political parties and the Islamic movements and the people are here today to deliver one message: that the minority with the loud voice cannot force their opinions on the silent majority of the nation," said Ahmed Mohamed, a member of the Islamic Jihad group.
In March, several constitutional amendments were approved with 77% of the vote. Credit for the victory was given to the Islamist groups, who preferred the changes to the drafting of a new constitution. These groups had warned voters that a vote against the amendments would have been "un-Islamic."
After the results were announced, some leaders of the Muslim Brotherhood declared their intentions to compete for about half of the parliamentary seats in the upcoming election. There are divisions within the group, however. The older guard of the party had decided not to field a presidential candidate, but the party's younger generation announced a candidate.
Friday's protests could heighten secular and democracy activists' fears that Islamists could gain in the upcoming elections.
There were fears of clashes Friday between the Islamists, who support the Supreme Council of the Armed Forces, and activists who have been staging a sit-in at the square since July 8 and have been calling for the head of the council, Marshal Mohamed Hussein Tantawi, to step down. The activists also demand a speedy trial for Mubarak and quick economic and political reforms.
Local media highlighted this angle. The front page of a government newspaper warned, "Egypt on the brink of a civil war," while a private newspaper read, "War is imminent in Tahrir Square."
The U.S. Embassy in Cairo warned its citizens not to go near the area.
There was no apparent military or police presence in the square or the streets around it.
The protest, dubbed "Friday of Unity," was announced several days ago after an agreement was reached between Islamists and the activist January 25th youth coalition. The agreement called for united demands, shared chants and slogans, and avoidance of controversial issues.
But on the day of the protest, the youth movement said it would not participate in the protest, asserting that the Islamists had breached the agreement.
"Today proves you cannot make a gentleman's agreement with Islamists," said one person. "Many Egyptians watching them on TV will not like what they see and will not vote for them in the upcoming election."
The protesters were told by their leaders to leave by sunset and not disturb the public or block traffic "like those blasphemous secularists," said Yasin Malek, an Islamist carrying a Saudi Arabian flag.