With a mass exodus of Christians from Mosul in the face of threats, the Chaldean Catholic Patriarch Louis Raphael Sako said that these Islamic militants are worse than Genghis Khan.
The Islamists are warning Christians that they must essentially convert or die.
"The heinous crime of the Islamic State was carried out not just against Christians, but against humanity," Sako told a special church service in east Baghdad where around 200 Muslims joined Christians in solidarity.
"How in the 21st century could people be forced from their houses just because they are Christian, or Shi'ite or Sunni or Yazidi?" he asked. "Christian families have been expelled from their houses and their valuables were stolen and ...their houses and property expropriated in the name of the Islamic State."Prayers are needed. Pray for those fleeing for their lives. Pray for those threatened for standing up for being a follower of Christ. And pray that the world will wake up to the horrific slaughter.
"This has never happened in Christian or Islamic history. Even Genghis Khan or Hulagu didn't do this," he said. Hulagu Khan led a Mongol army which sacked Baghdad in 1258, killing tens of thousand of people, destroying a caliphate which lasted nearly 600 years and leaving the city in ruins for centuries.