The Vatican's Pontifical Council for Interreligious Dialogue (PCID) urged Muslim leaders to condemn the Islamic State of Iraq and al-Sham (ISIS) in a statement released Tuesday.

The PCID, headed by President Jean-Louis Cardinal Tauran, said that the credibility of the leaders is threatened when they do not take a stand against the persecution of hundreds of thousands of citizens.

"The dramatic situation of the Christians, the Yazidis, and other minority religious and ethnic communities in Iraq demands that religious leaders, and above all Muslim religious leaders, people engaged in inter-religious dialogue and all people of good will take a clear and courageous stance," the statement read.

"All must be unanimous in their unambiguous condemnation of these crimes and denounce the invoking of religion to justify them."

Last week, an Iraqi official revealed that hundreds of Yazidi women – a religious minority – have been kidnapped, and are being held in schools across Mosul. Like the Christians and Shiite Muslims, the Yazidis have been persecuted because of their religious beliefs. Tens of thousands of Yazidis were driven from Sinjar this month, and the United Nations estimates that 50,000 Yazidis – including about 25,000 children – are living in the mountains.

In six months, over 5,500 people have been killed by ISIS – a terrorist regime that seeks to control Iraq and Syria.

The PCID pressed Muslim leaders to speak out against the atrocities.

"Otherwise, what credibility will religions, their followers and their leaders, have?" the Council asked. "What credibility could the inter-religious dialogue [which has been] patiently pursued in recent years have?"

Pope Francis called for international support for the droves of displaced Iraqis in a statement issued last week.

He urged all nations to "put an end to the humanitarian drama underway, adopt measures to protect those who are threatened by violence and assure them necessary aid, especially urgent for those who are homeless and depend on the solidarity of others."

The Pope also addressed the crisis last month during an Angelus prayer and address.

"Our brothers are being persecuted, chased away, they are forced to leave their homes without being able to take anything with them," he said from the balcony over St Peter's Square in Vatican City.

"I assure these families that I am close to them and in constant prayer," he continued. "I know how much you are suffering; I know you are being stripped of everything."

There were as many as 1.5 million Iraqi Christians before the United States invaded the country in 2003. An estimated 200,000 Christians remain, but that number is dropping as thousands flee the wanton violence.