More than half, and up to 80 per cent of Christians in Syria and Iraq have fled the regions since the Syrian civil war began.
The findings come from a report by Christian persecution watchdog Open Doors, alongside charities Served and Middle East Concern, analysing Christian displacement and movement in the Middle East since 2011.
Syria's Christian population has been roughly halved from two million in 2011.
Iraq's Christian population has fallen from more than 300,000 to 200,000-250,000 since 2014, and many more have been displaced internally, without leaving Iraq. In contrast Christians in Iraq numbered 1.4-2 million in the 1990s and before the Iraq war in 2003.
The report, titled, 'Understanding recent movements of Christians from Syria and Iraq to other countries across the Middle East and Europe', explores the data on Christian displacement and factors that motivate migration.
'Factors for leaving included the violence of conflict, including the almost complete destruction of some historically Christian towns in the Nineveh plains of northern Iraq, the emigration of others and loss of community, the rate of inflation and loss of employment opportunities, and the lack of educational opportunities,' the report said.
'While direct violence, such as the movements of ISIS in both Iraq and Syria, was the tipping point for displacement, the ultimate decision to leave the countries was portrayed as an accumulation of factors over time.'
In Europe, many refugees have fled to Germany in Sweden. In the Middle East, Lebanon is a common transit country, and around 250,000 displaced Iraqi Christians now reside in Lebanon, Jordan and Turkey.
The study noted that precise displacement figures, especially delineating Christian migration in particular, are hard to find. Its figures rely on educated estimates, but no absolute or proven statistics can be offered.
The full report can be read here.
