Pope Francis leaves after leading the Episcopal Ordination of Monsignor Fabio Fabene (not pictured) at Saint Peter's Basilica at the Vatican May 30, 2014. REUTERS/Giampiero Sposito
Pope Francis leaves after leading the Episcopal Ordination of Monsignor Fabio Fabene (not pictured) at Saint Peter's Basilica at the Vatican May 30, 2014. REUTERS/Giampiero Sposito REUTERS/Giampiero Sposito

The Christian community in Iraq was already under pressure to convert to Islam before the militant group Islamic State of Iraq and Syria seized large swathes of the area last June. According to reports, the number of Christians in Iraq has declined by up to two-thirds in a decade of sectarian oppression that followed the U.S. invasion of Iraq which resulted in the overthrowing of Saddam Hussein in 2003.

At least 100,000 Christians have fled their homes to escape ISIS persecution. Reports said Iraq is home to one of the world's oldest Christian communities. Many Iraqi Christians went to Erbil, capital of the Kurdistan region in Iraq, to seek shelter and hide behind walls of their church, CBC News reports. St Joseph's Church in the Christian Ankawa district has been turned into a refugee camp.

ISIS militants have declared Christians as their number one enemy in an updated version of its propaganda booklet "Dabiq." The cover photo shows the ISIS flag flying over the Vatican. ISIS reportedly wants to send a message to the world that it wants to "break the cross" and conquer Rome.

The Islamic prophet Muhammad had predicted that in order to pave the way for the coming of the Islamic messiah or "Mahdi", Istanbul, Jerusalem and Rome must first be occupied, according to some Islamic traditions.

ISIS' declaration of war comes amid the growing concern for the widespread persecution of Christians in the region. Reports said there are still 100,000 Christians in Iraq's capital city of Baghdad and they are currently at risk as ISIS advances.

Earlier this week, a joint conference between the World Jewish Congress and International Christian Embassy in Jerusalem was held to discuss the plight of Christians in the Middle East. In September, Father Gabriel Nadaf, who has advocated for the rights of Christian Arabs and support for Israel, told the UN Human Rights Council that 100,000 Christians were killed in the last 10 years. He said those who were not able to escape persecution at the hands of extremists were being treated as "second if not third-class citizens."

Repeated threats against the Vatican have prompted security officials to boost defences especially around Pope Francis in September. The threat of ISIS has forced authorities to restrict air space above the Vatican City, reports said. Pope Francis has previously compared the Jewish Holocaust and ISIS' persecution of Christians. He told the World Jewish Congress in a private meeting that the world was already in the midst of World War Three.