The threat follows the group's attack on a Baghdad church on Sunday in which at least 56 people died, including two priests.

The killings attracted condemnation and revulsion throughout the Muslim world. In Abu Dhabi, up to 1,000 Muslims and Christians are expected to attend a service tonight at St Joseph's Cathedral in memory of the victims.

Sunday's attack and the new threats have rattled Christian minorities throughout the region. But the call to eliminate Christians from Muslim lands is particularly menacing in Egypt, where growing divisions over the past few months have teetered on the edge of outright violence.

Leaders of Egypt's Christian community, about 10 per cent of the population, said the calls for bloodshed will have the opposite of their intended effect. Instead of instigating violence against Christians, they have jolted hardliners of both religions into rejecting violent rhetoric, which has escalated since the summer.

"People are reconsidering their situation and their positions and I suppose that they would rather protect Egypt from al Qa'eda than give al Qa'eda the chance to infiltrate and use them for other goals," said Yusuf Sidhum, the editor of Al Watani, a privately owned weekly that serves the Coptic Christian community. "Everyone stepped up and said it is high time to change this bloody rhetoric, which drags us in the swamp of sectarian strife."

Although Ayman al Zawahiri, al Qa'eda's second-in-command, is from Egypt, the Islamist militant group has never enjoyed much support in the country.

Recently, however, Egyptian adherents to the hardline Salafist school of Islamic thought have protested against Christian leaders. They say Egypt's Coptic Orthodox Church is holding two women who have converted to Islam, and object to what they describe as provocative statements by Christian Egyptian clerics.

For several consecutive Fridays last month, Salafis protested outside churches in Alexandria after Bishop Bishoy, a conservative Coptic priest, commented that Muslims are "guests" of Egyptian Christians, whose presence in the Nile Valley predates the birth of Islam by several hundred years.

Bishop Bishoy's comments followed equally incendiary ones by Mohammad Salim Al Awa, a conservative religious leader and the former secretary general of the International Union for Muslim Scholars. In mid-September, Mr Al Awa told audiences of Al Jazeera's Without Borders programme that Christians were stockpiling weapons in monasteries. He also alleged that Camillia Shehata, the wife of an Upper Egyptian Coptic priest, was being held against her will by church officials after she converted to Islam.

It was Ms Shehata's story, along with a similar allegation from 2004, that the ISI invoked when some of its members took over the Baghdad church on Sunday.

But instead of turning against Christians, calls to protect them echoed from throughout Egypt's Islamic community.

"This is something to be rejected and strongly denounced, and it serves none but those who want to spark discord and target national unity," the head of Al-Azhar University, Ahmed al-Tayeb, said.

Pope Schnouda III, the head of Egypt's Coptic Orthodox Church, used his weekly address in Cairo on Wednesday to praise Al-Azhar and the "sympathy" Christians have received from Egyptian newspapers, intellectuals and the ministry of interior, which has posted extra security outside churches.

Leaders of the Muslim Brotherhood, an outlawed Islamist group that represents the strongest opposition to Egypt's ruling political party, also strongly condemned the ISI and its statements.

"The Muslim Brotherhood is stressing to all, and primarily Muslims, that the protection of holy places of all monotheistic religions is the mission of the majority of Muslims," the group said.

Except for some isolated incidents, Egyptian Christians and Muslims have long enjoyed a peaceful relationship. But as Egyptian society has become increasingly conservative over the past decade, the relationship between the faiths has deteriorated.

The inter-religious dialogue reached its nadir early this year, when Muslim gunmen opened fire outside a church in Naga Hammadi in Upper Egypt, killing nine people.

Bishop Kirolos, the pastor of the Naga Hammadi cathedral, said yesterday he was confident that the Egyptian government would continue to protect the Coptic minority.

"We have lived in sectarianism since Sadat's time," Bishop Kirolos said, referring to Anwar Sadat, Egypt's president during the 1970s and whom many blame for empowering Islamists to counteract communists and socialists. "Now we are accustomed to this situation. Nothing more is going to happen."

Others, however, singled out Egypt's government for blame. Over the past decade, the Egyptian government has sought to mollify the radical Islamists within its borders by ignoring Salafi satellite television channels - which sometimes preach against Christianity - and teaching sectarianism in textbooks and classrooms, said Moneer Megahed, the head of Masryoon Against Religious Discrimination, a non-governmental organisation.

"Al Qa'eda is not supported by mainstream Muslims. Not now, not before. So there is nothing new in this," Mr Megahed said. "But what we need is to uproot sectarian violence and sectarian tension in Egypt. This can only be done by enforcing the law and changing the education system, how the media tackles the sectarian events and ultimately, by adopting a secular state."

mbradley@thenational.ae