Last year, for the first time in more than 2,000 years, there was no church service in Mosul after a radical Sunni Islamist terrorist group known as the Islamic State expanded its control into northwest Iraq. Christians living in their historic homeland in the Nineveh Plains were warned to either convert to Islam, pay a cumbersome tax or be executed.

I watched in horror as more than 10,000 Iraqi Christians, Yezidis and other religious minorities packed their belongings and fled to neighboring communities. This mass exodus represented the largest forced displacement in the Middle East since the Armenian genocide in Turkey more than 100 years ago. The persecution continued as the Islamic State burned churches and other religious sites, conducted summary executions, abused women and children and looted properties.