He used to be a Palestinian activist hurling stones at Israeli soldiers and dodging Israeli bullets. He then made a startling turnaround when he became a spy for the Israelis after witnessing Hamas leaders torture fellow Palestinians.

Mosab Hassan Yousef then found out about Jesus and became His follower, according to a God Reports blog.

Now, the former Hamas "terrorist" and Israeli undercover agent has become a peace advocate. He now preaches the gospel as he works to spread God's Word behind enemy lines.

He has also come out with an autobiography called "Son of Hamas: A Gripping Account of Terror, Betrayal, Political Intrigue, and Unthinkable Choices" where he detailed his stunning transformation.

"When any seculars come and tell me I'm doing this wrong, I tell them if you have five guys with my experience, let them come and we can talk. In Islam, I was one of the best Muslims. In Shin Bet, I was one of the best agents. To defeat its ideology, you cannot be politically correct. We need to go to their minds, their areas. Thank God for technology. We can outreach to everybody everywhere," Yousef told God Reports.

Yousef said he spent six years studying Christianity and comparing its teachings with Islam.

"It was a very difficult thing for me to do," he said. "I took the risks of the journey. At the beginning, I saw Jesus Christ as a great teacher. But later on, I adopted Him as my Lord, God and Saviour. It was a whole process."

Yousef said the battle for supremacy in the Middle East was spiritual more than military.

He knew very well what he was speaking, having been "born in the heart of Hamas" where he "was in every meeting for the Palestinian Intifada" before he became an undercover agent for Israel, working for the Shin Bet.

"Muslims have a great zeal for their god. They think they have God Almighty. They believe that if they go blow themselves up and kill a thousand Jews – or any infidel, anyone outside the body of Islam – to them, they are going to heaven, and they're having the 72 virgins, and they're having all type of fun and their crazy fantasy," Yousef said.

After embracing Christ, he realised that Islam is a "fake religion."

"The god of Islam is a liar," Yousef said. "I hope that I am not offending anybody. This is kind of dangerous to say, but I have studied Islam. My family started the Islamic Revolution in the Middle East. That was our business. This is still my family's business. After almost 20 years in Islam, I tell you that Islam is going nowhere. My family, my people are suffering the most because of this false teaching."

However, he said trying to defeat Islamic militants by waging war is just like "fighting a ghost." Instead of the never-ending violence, Yousef said, "We need to fight their ideology. We need to fight their fake god, their fake prophet. No government on earth can fight ideology. You can only fight ideology with another ideology. Today when I fight the god of Islam that represents hate and revenge, I fight him only with one God that represents pure unconditional love."

Yousef moved to San Diego in 2007 and joined the Barabbas Road Church. He publicly his embrace of Christ the following year and published his autobiography in 2010.