The Islamic State of Iraq and Syria (ISIS) followed today’s Friday prayers with a release of new documents in Mosul, ordering the city’s Christian community to either agree to convert to Islam or to pay the jizya tax, saying they face “death as a last resort.”

At one point Mosul had a fairly large Christian minority, estimated at over 3,000. Most are believed to have fled when ISIS first invaded, however, and it isn’t clear how many are even left.

The move appears to be in line with what ISIS did in Raqqa, where the Christian community entered into a dhimmitude agreement involving the payment of gold dinars (smaller amounts for poorer families) to remain Christian under ISIS rule.

Jizya was original intended as an equivalent to the Zakat payments Muslims are required to make, during an era when those charitable contributions were largely managed by Muslim states. The idea was that jizya would prevent the cost of the Zakat being a conversion obstacle. In addition to getting legal permission to continue to practice the non-state religion, jizya payers are traditionally also exempt from conscription.

Many Iraqi Christians, those who didn’t flee during the bloody US occupation, have fled northward, into Iraqi Kurdistan, and it is unclear how many remain at all in ISIS territory. In Syria, however, Christians have largely not been able to flee so easily, and ISIS retains a significant Christian minority in Raqqa and Deir Ezzor.