Horrific stories have emerged from Iraq of how Christians have been treated under the rule of Islamic State.

After ISIS seized control of Iraqi territory in 2014 and Iraqi resistance collapsed, Christians were told they should leave, convert to Islam or pay a special tax. Most fled, but according to testimonies collected from refugees in Jordan by religious freedom charity ADF International, those left behind were subjected to torture, forced conversion, sexual slavery and even crucifixion.

World Watch Monitor tells the story of Karlus, a 29-year-old cook who was unable to leave his home in Batnaya, a village outside Mosul, because he had to care for his disabled father.

When terrorists came to his house, they destroyed a cross and a picture of Jesus. "They even destroyed a piece from the Quran that was given to me by a friend," he said.

He was taken to a police station unconscious and held there for seven weeks after retaliating when one of the jihadists hit him in the face. During his detention he was was hung from the ceiling by a rope attached to his left foot. He was beaten and kicked and had salt rubbed into his wounds. He says he was also sexually abused by three women.

Karlus was told he would be shot dead but on the day his execution was due to take place he was released. He fled to Kurdistan, was treated in Spain for the injuries to his leg, and sought asylum in Jordan.

Another Christian victim of ISIS, Esam, a father-of-three from outside the Christian-majority town of Qaraqosh, said two of his wife's relatives had not managed to flee before the jihadis arrived. They were abducted; the husband has not been heard of since and the wife "now lives with one of the Daesh [ISIS] amirs".

Reports have emerged of thousands of Yazidi women being taken into sex slavery after ISIS overran the Sinjar region in August 2014, but Esam's account suggests Christian women and girls may have been targeted as well.

"We heard of 12 Christian girls who are with Daesh," he said. "They may be more. Our bishop told people not to tell if they lose their girls: it is a shame on the family."

Despite the progress made against ISIS in Mosul and its inevitable recapture, many refugees are too traumatised to contemplate returning to the region. Those who are able have applied for asylum in Western countries, among them the family of Esam's brother-in-law, recovering in Sweden.

"My wife's brother was crucified by Daesh," Esam said. "He was crucified and tortured in front of his wife and children, who were forced to watch. They told him that if he loved Jesus that much, he would die like Jesus."

Esam said the fighters tortured his relative for five hours; cutting his his stomach open and shooting him before hanging him on a cross.

Another refugee in Jordan, Alaa, who had fled with his family after receiving death threats, said it was "impossible to go back to Baghdad" after what had happened.

"It is not possible to go back to Iraq. I can't build a life there. I hope to go to Australia, but any country that will accept me, I will go there," he said. "I want to build a life and a future for my children."

The refugees' stories indicate the scale of the challenge facing Iraq after the defeat of ISIS, with not only the vast cost of restoring shattered infrastructure to deal with, but the legacy of terrible hatred.