Politicians and church leaders around the world have expressed their shock at the siege at the Syrian Catholic Church of Our Lady of Salvation in Baghdad on Sunday, which ended with at least 39 people being killed and dozens injured.
On All Saints Day, Pope Benedict told pilgrims in St Peter's Square: "I pray for the victims of this absurd violence, all the more ferocious in that it struck defenceless people united in the house of God, which is a place of love and reconciliation."
The pontiff said he wanted to renew his call for peace in the Middle East. "Confronted with atrocious episodes of violence which continues to tear apart the populations of the Middle East, I want to renew my call for peace," he said.
Armed militants wearing explosives stormed the church on Sunday while at least 100 parishioners were celebrating evening Mass, news reports said.
The terrorists first set off a car bomb across the street in front of the Baghdad Stock Exchange, which left at least two people dead. Then they stormed the church, killing another two people, according to reports.
Associated Press reported today that at least 39 people were killed, including hostages, Iraqi security forces and suspected militants. Other agencies have said 52 people dead and 56 people wounded.
One report said Iraqi church sources included three young priests among those dead.
The Syrian Catholic Patriarch Ignace Joseph III Younan was in Canada when the attack happened. In a statement, he criticized the lack of security for Christian places of worship and called on "Iraqi parties to overcome their personal and confessional interests and look for the good of the Iraqi people who have elected them."
"There are a few churches and Christian institutions left in Baghdad, not so great a number that it is not unreasonable for them to be protected, security-wise," he said, noting that the security being provided by the government is "far less than what we have hoped for and requested."
"Christians are slaughtered in Iraq, in their homes and churches, and the so-called 'free' world is watching in complete indifference, interested only in responding in a way that is politically correct and economically opportune, but in reality is hypocritical," said the patriarch, who served as bishop of the New Jersey-based Syrian-rite diocese in the United States and Canada from 1995 until his election as patriarch in 2009.
The patriarch demanded that the US Congress, the United Nations, the International Commission for Civil Rights and the League of Arabic States condemn the actions at the church and "take the appropriate action to defend innocent Christians brutally singled out because of their religion, in Iraq and some other Middle Eastern countries."
Chaldean Auxiliary Bishop Shlemon Warduni of Baghdad told Vatican Radio that at least one child was killed in the incident.
Bishops from Iraq had just participated in a special Synod of Bishops with `Pope Benedict at the Vatican. During the Synod, they said kidnappings for ransom, bombings of churches and other Christian buildings and a general lack of security have made life so precarious for the vulnerable Christian community that about half have left their homeland for safer destinations in the past seven years.
At least one bishop raised the question of systematic attacks as part of a "plan" to drive all Christians from the Middle East.
The cathedral and four other churches were the target of a string of bombings on 1 Augusty 2004, when parishioners were leaving Sunday Mass; 15 people were killed in those attacks.
The World Council of Churches general secretary, Rev Dr Olav Fykse Tveit, condemned the attack. He said: "The World Council of Churches strongly condemns the criminal act of terror that took place on Sunday in the Sayyidat al-Najat Church in Baghdad and expresses its deep sympathy and solidarity with those who lost their loved ones and pray for a speedy recovery for the injured.
The fellowship of the World Council of Churches is deeply troubled by the continuous suffering of Christians in Iraq and continues to stand in solidarity with all churches as they pass through turbulent and challenging times and witness to the love and peace of God in Jesus Christ even amidst hatred and aggression.
This is not the first time that such attacks have targeted Christian communities in Iraq. All those responsible need to be brought to justice, and governmental authorities should take their responsibility to bring safety and security to all citizens and particularly to those in vulnerable situation."
Tveit made these comments shortly before delivering the opening address at a high-level Christian-Muslim consultation, which takes place at the WCC headquarters in Geneva, Switzerland from 1-4 November.
The Anglican Vicar of Baghdad Rev Andrew White, told the BBC that Christians in Iraq has been more afraid of an attack since a pastor in America threatened to burn the Koran.