The statement by the leader of the Islamic State, Abu Bakr al-Baghdadi, warned that the Christians had until Saturday to “leave the borders of the Islamic Caliphate.”
“After this date, there is nothing between us and them but the sword,” the statement said.
The Islamic State in Iraq and the Levant, which is the previous former name for the Islamic State, captured Mosul as part of a large-scale offensive in July, which resulted in the declaration of a “caliphate” in parts of Iraq and Syria earlier this month.
Messages warning Christians about the ultimatum were announced through loudspeakers on the city’s mosques.
Church leaders advised the few families who wanted to negotiate with militants that they should also flee for their own safety. The exodus went on in Mosul throughout Friday, with all the Christians abandoning the town by the end of the day.
“Christian families are on their way to Dohuk and Arbil, [in the neighboring autonomous region of Kurdistan],” Patriarch Louis Sako told AFP. “For the first time in the history of Iraq, Mosul is now empty of Christians.”
The head of the Chaldean Catholic Church in Iraq said that, in recent days, the Islamic State militants had been tagging Christian houses with the letter N. which stands for “Nassarah” – the way Christian are referred to in the Koran.
“We were shocked by the distribution of a statement by the Islamic State calling on Christians to convert to Islam, or to pay unspecified tribute, or to leave their city and their homes taking only their clothes and no luggage, and that their homes would then belong to the Islamic State,” Sako said.
“We have lived in this city and we have had a civilisation for thousands of years – and suddenly some strangers came and expelled us from our homes,” a woman in her 60s told Reuters. On Friday, she had to flee for Hamdaniya, a mainly Christian town controlled by Kurdish security forces to the southeast of Mosul.
The events in Mosul, which is home to the tomb of the Biblical and Koranic prophet Jonah, echo the decree, which ISIS issued in the Syrian city of Raqqa in February, ordering the local Christians pay tax in gold and curb displays of their faith in return for protection.
Mosul lies across the Tigris river from the ancient city of Nineveh, at the heart of Mesopotamia. It used to have a Christian population of around 100,000 a decade ago, but the numbers decreased drastically due to waves of attacks on Christians following the 2003 US-led invasion of Iraq.
Locals estimate the town’s Christian population at around 5,000 ahead of the Islamic State takeover. But they said that all, except around 200 people, have left Mosul during the last months as it was controlled by the Islamists.