A Saudi Sheikh who was responsible for training ISIS jihadists has reportedly asked for a Bible having grown sick of the group's brutality, a missionary in the Middle East has said.

'Julian', who works with mission organisation Operation Mobilisation and has lived in the Muslim world for many years, told Voice of the Martyrs Radio last week about accounts of Muslims in the Middle East, including members of ISIS, coming to faith in Christ.

"God in his sovereignty is able to turn what is evil, and what the enemy intends for evil, into something that's good," he said.

He told two accounts of people linked to ISIS coming to faith that he had heard at a prayer event in Egypt. The first was about an ISIS fighter who had a vision of the cross. "For an ISIS fighter, that is not good news, that is bad news," Julian said.

The militant went online and came across a Christian website and became more interested. He left Syria and went to Turkey, where he met someone who was able to tell him more about Jesus, and he came to faith. He shared his testimony at a church conference in Lebanon.

Julian had also heard about a Christian taxi driver in Lebanon who was driving a Saudi Sheikh to the airport when he asked to stop to get a Bible. He drove him to meet a Christian worker in Beirut who gave him the Bible and asked him why he wanted it.

The Sheikh said he had been in Syria teaching the fighters "Jihad 101, the theology and practice of Jihad" and said he was "sick of the killing, there must be something better than this."

He also told the story of a Muslim Somali woman who had seen a beheading video of a jihadist killing an American while reciting the Qur'an and was horrified. It led her to pray to God and ask "Is this who you are? Is this what you want?". That night she dreamt of Jesus and saw that she was one of the worshippers. She and her husband both came to faith and she now works with the mission organisation.

"ISIS is being used to reveal something of the dark heart of Islam," Julian said. However he emphasised that "many, many Muslims want to distance themselves and are embarrassed by it and are great people and we really should not see our Muslim neighbours as terrorists, as ISIS, but as neighbours. Nevertheless some of this evil stuff is being exposed as never before."

He said these stories should move Christians to pray for ISIS militants, not against them. "These are people who have been deceived, they are lost... We need to pray for God to call forth...apostolic figures out of ISIS."