For nearly four years, their choice was to convert, pay a tax or die.
On Monday, for the first time since the jihadists in and around the Iraqi city of Mosul were chased out, Christians have been able to celebrate Christmas.
Hymns and cries of joy filled churches across northern Iraq, filled to the rafters by residents who had sought refuge in nearby towns to escape Islamic State's brutal rule.
But there was a bittersweet touch to the celebrations, with Christians wondering if their lives could ever be the same again.
Many of the tens of thousands of Christians from the Nineveh Plains have fled the country, seeking asylum abroad.
Fears of violence remain, with growing tensions in the north between the central government in Baghdad and the Kurds, who are pushing for independence
Worshippers in the town of Teleskof put aside their worries for a day to pray and receive communion from Father Salar Bodagh.
His church suffered minimal damage, unlike others in the region which had been looted and burned down by extremists.
In Mosul itself, Mass began with the recitation of the Iraqi national anthem.
Patriarch Louis Raphael Sako of Iraq's Chaldean Catholic Church said: "With this mass, we're sending a message of peace and love, because Christ is the messenger of peace."
On Christmas Eve at Saint Paul's church, Muslims stood with Christian worshippers and local officials surrounded by candles and Christmas trees.
The 2003 US-led invasion of Iraq had by 2014 pushed some 90 percent of Mosul's Christian population to flee, leaving only 2,000 families when it was captured by IS.
Iraqi forces finally expelled the jihadist group from Mosul in July after months of ferocious fighting.
Mina Ramez, 20, returned with her family two months ago, in time for the start of the new university year.