Many Christians captured by ISIS are sold as sex slaves, forced to convert or beheaded. But a Syrian priest who was captured by the Islamic militants in May has told of his incredible escape with the help of his Muslim friend.

"This is the miracle the Good Lord gave me — while I was a prisoner I was waiting for the day I would die, but with a great inner peace," the Syriac Catholic priest, Father Jacques Mourad, told Italian TV 2000.

"I had no problem dying for the name of Our Lord; I wouldn't be the first or the last, just one of the thousands of the martyrs for Christ," he said.

Formerly of the Monastery of Mar Elian in the Syrian town of Al Qaryatayn, Father Mourad was captured by ISIS on May 21 when the militants arrived in his town, 60 miles southeast of Homs.

"The first four days we were in the mountains, locked up in the monastery's car we were captured in," he said.

"On August 11 we were taken to near Palmyra, where there are 250 other Christian prisoners from the city of Al Qaryatayn."

Father Mourad was repeatedly asked to declare his faith and was threatened with death if he did not convert.

"Almost every day there was someone who came to my prison and asked me 'what are you?' I would answer: 'I'm a Nazarene, in other words, a Christian.' 'So you're an infidel,' they shouted. 'Since you're a Christian, if you don't convert we'll slit your throat with a knife.'"

Despite the threats, the priest said he refused to renounce Jesus Christ. Father Mourad credits a Muslim friend and the Virgin Mary for his escape.

"I want to thank all those who prayed for my liberation," he said.

"It's truly a miracle that a priest has been freed from the hands of the Islamic State. A miracle that the Virgin Mary worked for me."

However rather than fleeing Syria, Father Mourad is now determined to help his fellow captives who are still held by ISIS.

"Now I'm working with an Orthodox priest and other Bedouin friends and a Muslim friend to free the 200 other Christians who are still imprisoned," he said.

Mourad's monastery was the home to hundreds of displaced Syrians and worked with Muslim donors to help provide for their needs.

However when ISIS captured Al Qaryatayn in August, they destroyed the monastery.