By Noah Browning and Asma Alsharif
CAIRO (Reuters) - Rival camps struggling for Egypt's future radiated mistrust and hostility from competing mass protests in Cairo on Friday, with Islamists proclaiming justice as their only weapon and their opponents demanding the army fight terrorism.
Supporters and opponents of ousted Islamist President Mohamed Mursi evoked a battle of good against evil, exchanging vitriolic accusations of treachery in language suggesting the Arab world's biggest nation faces a long period of conflict.
"They call us terrorists, but justice is on our side. This is our only weapon," said Sherif Zeidan, holding up his pocket-sized Koran at a protest by tens of thousands of Mursi supporters.
Backers of Mursi's Muslim Brotherhood movement believe the army staged a coup when it removed Egypt's first freely-elected president on July 3 and installed a new government.
Across Cairo, by contrast, army attack helicopters banked low over Tahrir Square in a show of support for anti-Mursi crowds called out by military chief General Abdel Fatah al-Sisi, who deposed Mursi after only a year in office.
Sisi's call for protests - the first of its kind - has left Egypt more divided than at any time since president Hosni Mubarak was removed from power in 2011. The deep hostility raises the possibility of long-term uncertainty in a strategic U.S. ally at the heart of the Middle East.
Sisi, the most powerful man in the country, has asked Egyptians to give him a mandate to crack down on what he described as "violence and terrorism", seen as a veiled threat to the Muslim Brotherhood.
This call drew sympathy in the square, including among more pious Muslims. "We came out because we are delegating (Sisi) to fight terrorism," said 26-year-old Suhair Zaki, dressed in a full black robe and face veil. "He is the shield of the country that protects us."
Nationalistic songs blared and vendors sold Egyptian flags and portraits of Sisi at the approaches to the square, guarded by the military and riot police trucks plastered with stickers of the Egyptian flag reading "the people's police".
At the Rabaa al-Adawiya protest camp, the Brotherhood's main sit-in on the other side of the capital, many remained defiant, even though they see Sisi's call as a sign that a major military crackdown was imminent.
"Sisi will fall, the voices of the millions will drive him out," said Mohammed Jamal, 26, as he sold headbands in green, the color of Islam, that declared "Leave, Sisi!"
Drawing on state media, the army propaganda machine has been working overtime to deepen the Muslim Brotherhood's isolation. Privately-owned TV stations and newspapers, also deeply hostile to the Brotherhood, have been doing their part too.
One documentary screened on state TV on Friday showed celebrations that erupted the night Sisi announced Mursi had been deposed. The narrator declared it "the day of liberation from Brotherhood occupation".
One anchorwoman declared "God is Greatest" after the downfall of Mursi, who is being held incommunicado.
Scenes of military maneuvers, including with Sisi jogging at the head of a group of soldiers, were screened throughout the day. "Egypt against terrorism," declared an on-screen caption.
With its TV station closed down since Mursi was deposed, the Brotherhood has lost much of its media power. It has also been weakened by the arrest of many of its leaders.
Yet the group has been able to make its voice heard, using social media and the stage at its sit-in in northeast Cairo.
Mohamed Badie, the movement's leader, issued a statement on Thursday saying Sisi had committed a crime greater than knocking down the Kabaa, a building in Mecca which is the holiest site in Islam. The Brotherhood says it is committed to peaceful protest, even if it means death.
Addressing Mursi supporters, a top Brotherhood cleric urged the army to disobey any orders to open fire - something the army says it will do only against people involved in violence and terror. Sheikh Abdul Rahman al-Barr said Sisi had asked for a mandate "to spill the blood of innocents".
In language that could just as well have been heard on Tahrir Square, he said Egypt was caught between a group "seeking good, and a group seeking evil".
(Editing by Tom Perry, Michael Georgy and David Stamp)