So many Christians have left Iraq that the country's many historic sites of Christian interest will be little more than tourist attractions, says one church leader.
The Chaldean Archbishop of Erbil, Bashar M Warda, told Release International that Iraq's Christians have "lost their trust in the land and in the future" following years of hardship after the 2003 invasion and the latest ISIS onslaught.
"June was the first month in 1600 years in which Mosul did not celebrate any mass. The attack on Christians has been immense. In the future I imagine Iraq becoming a country where you have many Christian sites, just for tourism – due to the families that are leaving," he said.
ISIS has taken over large parts of Iraq, triggering a mass exodus from the region. Those fleeing included tens of thousands of Christians who left their homes with only a few possessions.
There have been reports of terrible reprisals for those who do not obey the strict Sharia rules imposed by the militants, including beheadings and crucifixions. One man was reportedly forced to watch his wife and daughter be raped and killed by militants after the Christian family said they could not pay a poll tax for non-Muslims.
Middle East Concern was reporting that Christians had been given an ultimatum this week to "leave or face execution by midday Saturday".
'The terror is palpable and that fear is driving Christians from their homes," says Release Chief Executive Paul Robinson.
"If ISIS behave true to their form in Syria, then the Christians who remain in Iraq under their control can expect to live a life of subjugation under their brutally-enforced variation of Islamic law, and to have to pay for the privilege."
The Kurdish region's newly-appointed Religious Affairs Minister, Kamal Muslim, told Release that only 50 Christian families remained in Mosul at the time ISIS gave its ultimatum to get out or be executed.
"Kurdistan will always be a safe haven for those leaving their places of terror," he promised.
Human Rights Watch said it had also received reports of all Christians being ordered to convert, pay "tribute" money, or leave Mosul by July 19.
ISIS followed the decree up with orders barring Yazidi, Christian and ethnic Kurd employees from returning to their government jobs in Mosul.
Iraqis have told HRW of militants pillaging homes and places of worship, and marking the properties of minorities, including Christians.
"ISIS should immediately halt its vicious campaign against minorities in and around Mosul," said Sarah Leah Whitson, Middle East director at Human Rights Watch. "Being a Turkman, a Shabak, a Yazidi, or a Christian in ISIS territory can cost you your livelihood, your liberty, or even your life."