First, Islamic State in Iraq and Syria (ISIS) turned its weapons on fellow jihadists fighting to overthrow Syria's Bashar al-Assad. Then, it proclaimed a "caliphate" in parts of Iraq and Syria that was widely criticised across the Muslim world.

Now, ISIS is forcing non-Muslim Iraqis to convert to its distorted version of Islam or leave their homes, under the threat of execution.

Since early July, UN and international media reports have chronicled religious minorities across northern and western Iraq, including Christians in Mosul, seeking to flee as ISIS fighters demand they convert to ISIS's brand of Islam or leave.

Those choosing to remain were threatened with execution "by the sword" in an ISIS statement, AFP reported.

When ISIS overran Mosul in June, it demolished shrines and mosques and took ownership of non-Muslim places of worship.

"It is completely un-Islamic"

"No prophet has said, 'I have come for Hindus, I have come for Muslims, I have come for Christians,'" Kazi Nurul Islam, founder and former chairman of the World Religions Department at the University of Dhaka, told Khabar. "They said that they came for humanity, for everyone. This is also the teaching of Prophet Muhammad (PBUH).

"But ISIS is forcing and threatening Christians in Iraq to convert to Islam or face death. It is completely un-Islamic and unkind. It can be treated as a terrorist activity."

Sri Lanka's All Ceylon Jamiyyathul Ulama (ACJU) Media Secretary Shaikh Fazil Farook told Khabar that Islam does not support forced conversions.

"No person could be forced to embrace Islam, according to the Islamic teaching as Allah says in the Holy Qur'an in Chapter 2, Verse No. 256," Farook said. "There is no forcing in our religion. If one is to embrace Islam, it should be out of his own will."

He stressed ISIS's actions were an outright abuse of Islam. "During Prophet Muhammad’s time, Christians and Jews practiced their own religion alongside Muslims and no one was forced to convert to Islam."

"A crime against humanity"

Maulana Hizfur Rehman, head Imam at Delhi's India Islamic Cultural Centre (IICC) Mosque, said such behaviour draws severe repercussions in the Qur'an.

"Forcible conversion, asking people to leave their homes and frightening them is a crime which is punishable by death according to the Holy Qur'an," Rehman told Khabar. "Those who do it in the name of Islam are enemies of Islam and their final abode is hell. Muslims should unite to condemn these acts through all means across the globe."

Indonesian Ulema Council (MUI) chairman Din Syamsuddin told Khabar Islamic does not teach killing.

"ISIS does not have the authority to kill people under the name of a 'caliphate'," Din told Khabar. "Any systematic attacks that can cause suffering for civilian populations because of their ethnic background or religious beliefs are not only against Islamic teachings, but also a crime against humanity.

"Whoever does this must be held accountable. MUI has stated earlier that we are not supporting ISIS's caliphate."

Communion of Churches in Indonesia (PGI) chairman Andrew A. Yewangoe hopes the international community will find a situation.

"In the meantime, we are sending our prayers for our brothers and sisters, who are currently facing these difficulties, for those who are persecuted, forced to leave their houses and who end up dealing with hunger and uncertainty," he said.

The UN Security Council on July 22nd announced widespread or systemic attacks directed against people because of ethnic background, religious beliefs or faith "constitutes a crime against humanity for which those responsible must be held accountable".

Jakarta resident Mardianto Mamdani said ISIS's actions show the group is not part of Islam.

"They are criminals who use religion to get what they want," he said. "They are greedy, abusive and intolerant. There is nothing like that in Islam. Not at all."

Shahriar Sharif in Dhaka, Munza Mushtaq in Colombo, Altaf Ahmad in New Delhi, Aditya Surya and Alisha Nurhayati in Jakarta contributed to this report.