BBC reports have described ISIS ambitions to create an Islamist caliphate spreading from northern Iraq across to north-west Syria. If ISIS can hold Mosul and consolidate its presence there, it will have taken a giant step towards its goal of creating an Islamist region, controlled by insurgents, that connects Iraq and Syria.

Apart from the overall population being targeted, in the past there has also been ISIS violence explicitly aimed at Christians.

Before this week's attacks about 300,000 Christians were estimated to live in Iraq, out of more than 1.2 million at the beginning of the 1990s. Since then, large numbers have either fled abroad (Jordan, Lebanon and Syria) or to the northern Kurdish region as a result of the severe anti-Christian violence; e.g. church attacks, kidnappings, killings, robberies, rapes and threats.

This exodus of Christians means a loss of pluralism and an increase of intolerance in an already divided Iraqi society.

The Archbishop of Mosul Amel Nona said that in the 11 years following the 2003 US-led overthrow of Iraq's President Saddam Hussein, Christians in Mosul had declined from 35,000 to 3,000. This week, Mosul's last remaining Christians had left their homes, he said.

Describing reports of attacks to four churches and a monastery in Mosul, the Archbishop said: "We received threats... [and] now all the faithful have fled the city. I wonder if they will ever return there."

Some reports, however, say Christians have already returned to Mosul, while other sources claim that all have fled and are unlikely to return.

An organisation partnering with Christians in Iraq has told World Watch Monitor that some families who fled Mosul decided to return due to being unable to find refuge and fearing street fights between the Iraqi Army and the ISIS forces: "some families mentioned it is better to die at home than staying on streets."

Chaldean Priest Qais Kage told Fides Agency, "The advance of the ISIS militiamen is favoured by large tribes and Sunnis clans. What happened in Mosul is significant: such a big city cannot fall in a few hours without support from within. The chaos and political division of the country, due to sectarian conflicts, promotes the advance of the militants who have come from outside: the Iraqi army has left everything in their hands."

Kurdistan and the rest of Iraq

Iraq is divided in two parts, the semi-autonomous Kurdish region in the North, officially governed by the Kurdish Regional Government (KRG) based in Erbil and the large remaining Arab part, controlled by the Iraqi Government in Baghdad. Kurds and Arabs have their own languages and culture. Most of Iraq's oil resources are found near Kirkuk and Mosul, the border areas between the Kurdish region and Arab Iraq, and these are amongst the most violent places of Iraq. Christians are caught here in the crossfire of two different battles: one for a Kurdish autonomous country and one for a religious cleansing of Iraq by Islamic terrorist groups who wish to make the country purely Islamic. The Kurdish aspiration for sovereignty - a desire three Sunni provinces in Arab Iraq have expressed as well - could well be one of the most destabilising factors for Iraq.

Fleeing to Kurdistan

While the north of Iraq has been developing into a more and more dangerous place for Christians, those who flee to the Kurdish region are now considered refugees inside Iraq.

As refugees they face high unemployment and inadequate housing, plus difficulty in finding schooling (especially university) for their children, inadequate medical care and monthly food rations due to registration problems and discrimination.

ISIS increased extremist Islamic pressures

Iraq remains at number four of the 50 countries listed on the World Watch List ranking the most difficult nations for Christians to live. The list is published annually by Open Doors International, a charity supporting Christians worldwide who live under pressure because of their faith. The situation for Christians in central and south Iraq is as bad as last year, however, the north is developing into a more and more dangerous place for Christians.

The main persecution 'engine' in Iraq, says Open Doors, is Islamic extremism. Islamic extremist groups desire a religious cleansing of Iraq and wish to make the country purely Islamic. Since the US led invasion of Iraq in 2003, the situation has continuously deteriorated due to considerable levels of violence by Islamist militants and insurgent groups. Prohibited under Saddam Hussein, Islamist political parties - Shiite and Sunni - have made their entry to politics and even constitute the majority in parliament.

Since 2003 anti-Western and anti-Christian sentiments tend to go hand-in-hand. These Islamist groups have increased in number in the North, under the influence of the civil war in Syria. One of their aims is fulfilling jihad and thus resulting in annihilation of the country's Christian population. This situation is aggravated by government impunity.

According to Open Doors International, in general, Iraqi society has increasingly become more Islamic. There is an increase in social control of women, the wearing of the headscarf and observance of Ramadan. Even Christian women in Baghdad and Mosul have been forced to veil themselves in order to move safely outside of their homes.

Explanation of background of ISIS

The group ISIS is an Iraq and Syria-based Sunni extremist group. ISIS follows an extreme interpretation of Islam, promotes sectarian violence and targets those with other opinions as infidels and apostates.

In October 2004 ISIS-leader Abu Musab al-Zarqawi, pledged allegiance to Osama bin Laden. This made the group an affiliate of al-Qaeda. In the first year of the war in Syria, late 2011, ISIS engaged in that war through one of the groups that originally assimilated into ISIS: Jabhat al Nusra. Between the leaders of ISIS and al-Nusra grew a division. This led to a split between the two jihadist groups and later caused infighting between both groups.

The current leader of ISIS is Ibrahim Awwad Ibrahim Ali al-Badri, the man is also known as Abu Bakr al-Baghdadi or Abu Du'a. ISIS is said to have only some 2500 Iraqi and foreign members in Iraq and some 5000 in Syria, both Syrians as well as many foreigners. ISIS also operates in Lebanon and Turkey.

ISIS has undergone several name changes ranging from the Islamic State of Iraq and the Levant (ISIL) also known as Islamic State of Iraq and al-Sham (ISIS, this abbreviation is mostly used) or in Iraq as Da'ash.

The role the Syrian conflict plays in Iraq

ISIS has said it wants to establish an Islamist-led state (or Caliphate) which straddles across both Iraq and Syria.

The role of the civil war in Syria is significant: it led to a rise in recruitment and funding of Al Qaeda inspired groups in Iraq in 2013.

In the current instability in Syria, the position of Islamist radicals and ant-Christian attitudes should not be underestimated, according to Open Doors. ISIS is now better established in Syria, so Syrians seem to be pressured to choose between Assad and Islamist radicals.

From ISIS-controlled regions in Syria's northern city of Raqqa reports of Christians have emerged of them being given an ultimatum of converting to Islam, being killed or signing a 'dhimmi contract'.

The contract is an integral part of traditional Islamic sharia law dating back to medieval times and requiring non-Muslims, in this instance Christians, to pay protection money which only allows them to gather for worship in churches.

Under the dhimmi contract, public expressions of Christian faith are not allowed. These prohibitions include: Christian wedding and funeral processions; ringing of church bells; praying in public and scripture being read out loud for Muslims to hear; Christian symbols, like crosses, cannot be displayed openly; churches and monasteries cannot be repaired or restored irrespective if damage was collateral or intentional; and Christians are also not allowed to make offensive remarks about Muslims or Islam.

The dhimmi contract also enforces an Islamic dress code, like the veiling for women, and commercial and dietary regulations, including a ban on alcohol.

According to Open Doors, about 20 Christian leaders have signed to contract in Syria. If they keep these rules and live as dhimmis, they will be protected. If not, they will be 'put to the sword'.

Source: World Watch Monitor