His book, "Son of Hamas", is currently No 11 on the New York Times' list of hardcover nonfiction bestsellers.
"What I can say about 'Son of Hamas' – which I believe it's not my story it's God's story, and it's His project – I wish it would be successful because it's His project," says 32-year-old Yousef, whose father, Sheikh Hassan Yousef, was a Hamas founder and leader who spent numerous years in Israeli prisons.
Released on March 2, "Son of Hamas" unveils the truth behind Yousef's secret role in the terrorist organisation and his journey to a new faith that instructed him to love his enemies.
"It's good news," Yousef told members of the National Religious Broadcasters last week during their annual convention.
"All the time we hear Hamas killing Israelis, and Israelis killing Hamas. This top Hamas leader is assassinated. And this Israeli bus was blown up. This is what we hear from the Mideast," he said.
"This is the time that we hear that son of Hamas saved Israelites. This is a message of hope – not because son of Hamas is a great person, but because son of Hamas followed the steps of a hero, my hero, Jesus Christ."
Though Yousef said he was an integral part to Hamas and withstood torture in prison for the movement, he eventually began to question who his enemies really were after he discovered that Hamas was torturing its own people in a relentless search for collaborators.
After a chance encounter with a British missionary in 1999, Yousef started a six-year quest that jeopardised Hamas, endangered his family and threatened his life.
In his book, Yousef tells the story of the agonising decisions that led him to walk away from his family, friends and homeland – which he still loves and prays for today, although he has since been disowned.
After it became public that Yousef served as a spy for the Israeli security agency Shin Bet, his father released a statement saying, "I, Sheikh Hassan Yussef ... my wife, sons and daughters announce that we have completely disowned the man who was our oldest son and who is called Mosab."
Despite this, Yousef says he continues to love his family – "not because of who they are, but because of who my God is."
"I love them so much," says Yousef. "When I think about Muslims, I think about my family. I'm not going to give up on them. They disowned me. I will not disown them."
Yousef is urging other believers to pray for Muslims, who he says are "wonderful people" whose humanity has been "unskinned" by the Islamic ideology.
"Our problem is with their god (the god of the Koran). Our problem is with their ideology," he says. "Please understand the difference between Islam and Muslims."
Yousef told The Daily Telegraph that he is convinced that speaking out about the problems of Islam and the "evil" he witnessed back home will help to address the "messed-up situation" in the Middle East and one day bring about peace and enable him to return.
Presently, Yousef is residing in San Diego, California, where he works as a security guard at a grocery store and attends Barabbas Road Church, a Baptist church that knows him by his English name – Joseph.
He was the oldest of six brothers and two sisters.