A Christian woman arrested in Iran for her faith became an instrument for conversion after her Iranian interrogator known for persecuting religious minorities surprisingly gave up his Islamic faith and embraced Christianity instead.

Noushin, who was forced in solitary confinement for three days in the Muslim-dominated country, said all she did was to share the Gospel to her inquisitor, according to the Gospel Herald.

"We talked about Jesus for hours until finally the interrogator gave his heart to Jesus. We prayed together," she recalled.

"It's an honour for me to talk about Jesus," Noushin told the guard. "You also need Jesus in your life. I cannot be indifferent toward you. I want you to experience the joy and blessing of salvation. I can't keep silent about this."

Noushin said at first she thought her detention would make her give up her faith.

"I wasn't ready to go to prison," she said. "I knew it was a dirty place, a place where people are tortured and locked up in solitary confinement. I was afraid that I would be so fearful that I would give up all the names of the members of house church. I even feared that I would deny my faith if they tortured me."

According to Open Doors, a faith-based group helping persecuted Christians worldwide, the Gospel continues to be spread throughout Iran despite the persecution of thousands of religious minorities, including Christian converts, under President Hassan Rouhani's government.

"The government of Iran continues to engage in systematic, ongoing, and egregious violations of religious freedom, including prolonged detention, torture, and executions based primarily or entirely upon the religion of the accused," the US Commission on International Religious Freedom reported.

"Over the past year, there were numerous incidents of Iranian authorities raiding church services, threatening church members, and arresting and imprisoning worshippers and church leaders, particularly Evangelical Christian converts," the commission's report also read. "Since 2010, authorities arbitrarily arrested and detained more than 500 Christians throughout the country."

Many of Iran's Christians, who make up less than 1 percent of the population, face charges related to "home church activities."

"Iranian religious authorities prefer that they [converts to Christianity] leave Iran because the authorities can't control them," said Iranian Christian Morad Mokhtari, who fled the country in 2006. "Just their name is evangelism. Imagine someone says he is a Christian and has a Muslim name."

The US Commission cited Sunni Muslims, Sufi Muslims and dissenting Shiite Muslims as among those who have been imprisoned.