Two pastors from South Sudan who were freed after a terrifying prison ordeal where they even faced a possible death sentence have spoken movingly of how their Christian faith sustained and inspired them during their time behind bars.

Pastor Peter Yen and Pastor Michael Yat preached the gospel to fellow inmates and brought men on death row to faith in Jesus Christ. 

The two men were imprisoned in Sudan in December 2014 and January 2015 on six charges including espionage, "offending Islamic beliefs", promoting hatred among sects and undermining the constitutional system. They were freed last summer after a hearing in Khartoum.

The pastors now state that those who imprisoned them "blessed us mightily", according to interviews they gave to the charity Open Doors and seen in full by Christian Today.

Pastor Peter, who grew up in a non-Christian family and as a young boy attended church with friends, described how his trust in God was formed when he was a child and was accused of stealing from a shop. "I was devastated and questioned God about His faithfulness. When I went back to the village, I found that the real thief had been caught and had confessed. This taught me to trust God and it proved to me that He is real and active. I have been a believer since then."

He became a pastor in the Presbyterian Evangelical Church and worked in cross-cultural evangelism with Pastor Michael and was sent to Khartoum when civil war broke out.

He worked in outreach, discipleship, and leadership in spite of knowing the risks of doing such work in an Islamic country where Sharia is law and anyone who leaves Islam risks the death penalty for apostasy.

When Pastor Michael was arrested in December 2014, Pastor Peter went to the Religious Affairs office to inquire about him and security officers found the link between them, leading to his own arrest.

He said he was held separately from Pastor Michael in Kober prison and accused of converting Muslims.

"I told them as a pastor it was my duty to preach the gospel wherever I went but that ultimately it was God who changes human beings. They insisted that the people on the list were still Muslims because their names had not changed, but I explained that Christians are not concerned about names but about the transformation of a person's heart.

"After about four hours I was taken into a darkened cell at Kober, where I stayed for three months. This was the most difficult time for me. I did not know that Michael was in the same prison.

"The only contact I had with anyone was when food was passed to me through a very small opening in the door. I was not allowed to read my Bible or any other books.

"They would blindfold me to take me to interrogations. When the blindfold was removed, I would find four soldiers with guns pointing at me. They tried to coerce me into becoming a spy."

They were both then moved to another department where they stayed for two months in cells measuring two-by-six metres holding up to 20 people at one time.

"The heat was almost unbearable. We could not sit down, because there was no room. We also had to buy our own food and were often overcharged. But we were able to talk to our loved ones occasionally. The best part about being there was that we were able to get Bibles and preach to fellow inmates."

After being charged officially they were relocated to Omdurman Prison.

"Here we found a church in the compound with over 3,000 prisoners. This was our mission field! Pastor Michael and I worked out a schedule to preach with the permission of the prison officers who were very good to us. That is until a foreigner came to the prison and was caught taking pictures of the premises. After this the prison officers changed drastically. They ordered us to immediately collect all our things because we were being moved right away."

They were taken back to Kober prison.

"They confiscated our Bibles and chained our legs. The chains stayed on for two weeks, during which we showered in our clothes because we did not know how to remove them with the chains. We were not allowed to go out except for the daily bathroom breaks of one hour. We pleaded with them to give us back our Bibles and they finally agreed on condition that we did not preach to anyone.

"Michael and I spent only one night in the same cell before being separated again and would meet during the one hour bathroom break only.

"The conditions were very hard here. This prison was so hot that you could wring sweat out of your shirt. But it was the best place and the happiest phase for me because I was put in the same cell with condemned persons and had opportunity to preach to all.

"Most of them were Muslims. People asked me why I was there and when I told them I faced the death sentence for being a preacher, they would say, 'But if they are going to kill you, why are you so happy?'

"It gave me the opportunity to share about heaven and about Christ. They were shocked and wanted to know more. Whenever the prison officers realised that we were preaching to fellow inmates, they would take us to other cells. We did not mind this because in this way we got access to almost all the condemned persons! God surely has His ways of doing things, even using those who think they are punishing you."

They came to trust God's providence.

"We made peace with the reality that God would either get us released or let us be killed. The outcome was fully in His hands and we placed our faith in His ultimate purpose.

"When the judge read the 45 minute long ruling, we sat there in peace waiting for whatever was to be. He criticised the security agents for the way they treated us – keeping us in custody beyond the stipulated 24 hours, holding us incommunicado, going to our homes without warrants of arrest – but when he declared us free, I thought I was dreaming! I could not believe my ears! I looked at Michael and asked in disbelief, 'Did he just release us?!' and he confirmed that I had heard correctly."

He believes God had reasons for allowing them to go through all that suffering.

"Through our experiences condemned persons heard the gospel. Of those we led to Christ, two were hanged while we were still there. Another three were killed soon after we were released. It was comforting to know that they went to be with Christ.

"Also, the situation of the church in the Sudan was highlighted and people around the world became aware of the pressures Christians face there. If our imprisonment was God's way of exposing their suffering so that they can receive relief and prayer support, it was worth it."

Pastor Michael said: "We should not be surprised by suffering. God has prepared us for such things."

A pastor's son, he said he received Jesus when he was about 10 years old.

"A boy who stole my brother's bicycle beat me when I tried to take it back. I was very upset about the whole thing and could not eat or sleep. Surprisingly, I started feeling convicted to forgive this boy. When I did, I experienced great peace.

"That is when I decided to give my life to Christ. Until today, this principle of forgiveness has continued to play an important role in my life."

Pastor Michael studied theology in Egypt, after which he served as evangelist, pastor, and teacher in Sudan and South Sudan.

When the civil war broke out he fled to Uganda but in December 2014 he and his wife went back to seek medical care in Khartoum for their youngest child.

"On the first Sunday after our arrival, I told Mary I wanted to go to Bahari Evangelical Church because I was eager to learn how the brethren were doing in the midst of a serious conflict. She asked me not to go because she felt uneasy but could not explain why. I insisted, and I took with me my phone, iPad, memory stick, and notebook. For some reason I gave Mary all the cash I had on me. If it had not been for that, she would have been stranded."

He ended up preaching, and his sermon was recorded by security officials, which led to his arrest.

"They questioned me about our work and why we had Muslims claiming to be Christians. They also found information about the indigenous pastors we worked with and a map of Sudan where we had indicated our work. They said it was proof I was spying for South Sudan. They also planted security training materials on my laptop and claimed it had been there since 2010."

In Kober prison Michael was placed in a cell with 17 other people. Instead of complaining he said: "That was a perfect evangelism opportunity."

He said he survived in small cells by taking turns sleeping. "Six would sleep for four hours, wake up and sit while the other six slept. This is how we slept the whole time we were there. I cannot describe the heat and horror of the hygiene situation. There were no windows in the cells, yet temperatures would normally reach 50°C.

"Also, all prisoners would only be allowed out for one hour per day during which we had to bath, use the toilet, and then return to the cell. But there were only three toilets. It is a true miracle that we did not get sick. It is God who protected us. During this time I held on to Romans 8:18-39."

He said they were held with all kinds of people, from petty criminals to hard-core criminals, and were able to talk to them about Christ.

During their final hearing last August, Pastor Michael was found guilty of "breach of the peace" and Pastor Peter of "managing a criminal or terrorist organisation". They were released because they had served their sentence during the previous eight months in prison.

Pastor Michael said he had been moved by the support the two received.

"The Christians in Sudan came together and prayed for us. They united across denominational barriers. Knowing this was a big blessing."

To others facing persecution, he said: "Do not be surprised by your persecution, or discouraged. Do not look for the cause of your suffering. Instead focus on the fact that Christ will never abandon you. He is called Emmanuel, God with us. Hold on to Him, and if He so chooses, He will cause you too to be freed from the suffering, as He did for us. Your testimony will serve to encourage other believers. Do not give up hope. Finally, may God comfort you the same way He comforted us while we were imprisoned."

Pastor Michael pleaded with Christians around the world to continue praying for Sudan. "Please continue to pray for Sudan. Many are weak and remain weak under the constant government pressure. They need training, prayer and support. Pray for strength to all who are involved in church ministry."