Imprisonment, beatings and even death—those things don't scare newly converted Christians in Iran anymore as their number continues to grow at an amazing rate.

According to the reference book Operation World, there were only about 500 Muslim Background Believers (MBBs) in 1979, when the Islamic revolution swept to power in Iran. MBBs refer to people who converted to Christianity from Islam.

Now, Operation World estimates that at least 100,000 MBBs are now in Iran, with some sources even placing the number as high as 1 million.

How could Muslims turn their backs on the faith they have grown with? What's happening in Iran?

Mark Howard of Elam Ministries explained the phenomenon to CBN News in a recent interview. He said two main factors are involved: dissatisfaction with the harsh Islamic regime coupled with disillusionment with Islam in general and the bold outreach by Christians inside the country.

"I think first and foremost we have to acknowledge that many people have been praying for Iran for a long time and that the Lord is doing something special in that region," he said.

His group, Elam Ministries, was founded with the main objective of strengthening the Iranian church both inside the country and among the diaspora living in the Middle East and Europe.

Writing in a blog on The Gospel Coalition web page, Howard said Iranians from various social backgrounds—including hardened criminals, Muslim imams and abused women—have come out with compelling testimonies on how they found faith in Christ.

One of those who revealed how they found Christ is Fatemah, a young Muslim girl who had been sexually abused by her brothers. When she was 11 years old, she said her family sold her into marriage, but soon her husband divorced her and sent her back to her family. Facing the prospect of more sexual abuse from her own kin, Fatemah ran away and began living on the streets.

It was there that she heard about Jesus and she readily gave her life to Him. She eventually married a Christian man.

When the couple attended a ministry training session hosted by Elam Ministries, Fatemah felt that the Lord was telling her to go back and minister to her family. Despite misgivings from her husband, Fatemah returned to her family.

To her surprise, her family listened to her Gospel message. Even more surprising, her parents and siblings all followed her and embraced Christ, too!

Now, they have turned their home into a house church with Fatemah as one of the Christian leaders in their community.

Howard said Fatemah's story demonstrates not just the saving power but also the transforming power of the Gospel.

"The Lord saves us, but the Gospel's also full of the power to redeem and the power to restore and to bring reconciliation and her testimony really speaks to that and shows it in a very powerful, tangible way," he said.