At the height of the brutality of ISIS and Islamic radicalism, Sohrab Ahmari announced he was converting to Catholicism, a shocking admission for someone who grew up in an Islamic household in Iran.

Ahmari, 33, now an op-ed editor for the New York Post and a contributing editor for the Catholic Herald, shared his unlikely faith journey from atheism under the Islamic Republic and Marxism in his teens on "The Story with Martha MacCallum" Wednesday night. While living in a nominally Muslim home in Iran, Ahmari said he was pushed away by the hypocrisy and the double-life his family had to live – acting one way in public but another behind closed doors.

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"That hypocrisy and that sort of sense of living a dual-life I found very repulsive, so when I was 12 or 13, I just decided that if this is God, I want nothing with it and he must be something for simple people," Ahmari said.

As a teenage atheist, Ahmari moved from Tehran to Utah. He said at first, he joked that he moved from one theocracy to another, which he now admits is an "unfair comparison" because in Iran enforcement was through flogging but in America, it was democratically elected.

The pendulum swung from one extreme to another for Ahmari. He was initially drawn to socialism and Marxism.

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"I discovered Marxism as a way to answer all of life's questions because Marxism is this totalistic understanding of the world," Ahmari said. "Like every element from art and culture to economics, it has an answer to everything. It's a very horrible answer in some ways. It has no sense of human nature, of the soul. It denies all of that. It says everything is material. At the same time, Marxism has a religious dimension, so even as I was professing Marxism, in some ways, I was still looking for God."

But it was at the age of 23, after a series of bad choices one weekend, Ahmari stumbled into a mass in the heart of New York City, and that's where it all changed -- yet again.

"I had this astonishing experience that there was a mystery that is underway, in the process of the holy mass, is the presence of God in a very powerful way," he said.

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And for some time, Ahmari went back to living one way internally and another on the outside.

"This was even while I would say outwardly I'm an atheist," he admitted. "I'm too smart to be a believer. I'm not one of these people, but internally the level of my imagination, my emotions, I thought this is true, and whatever redemptive thing is happening here, I want it. But it took still a long time to finally ascent to faith."

But in 2016, after ISIS took credit for slaughtering a priest at the altar of a Roman Catholic Church in Normandy, Ahmari had had enough.

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"That act, when that happened, I was so outraged by it, that I thought I have to say something, and so like most millennials, I took to my Twitter account and I said, 'this is atrocious and, oh, by the way, I'm studying to become a Roman Catholic.'"

Ahmari was flooded with questions and that's when he decided to share his full story in a new book, "From Fire, by Water."