Onsi Kamel grew up as an evangelical but became highly attracted to Roman Catholicism. In time, though, he discovered that what had attracted him so much about Catholicism could not necessarily be found in the Roman Catholic Church. And that it could be found in the theology of the Protestant Reformation.
He tells his story in an article Catholicism Made Me Protestant, published, somewhat surprisingly, in First Things. He tells about his love for the Church Fathers and then his discovery that the Church of Rome does not necessarily hold to what they said. He greatly appreciated the writings of Cardinal Newman, the Anglican pioneer of Anglo-Catholicism who then took the step of going over to Rome, which made a saint of him. But Kamel became concerned with Newman’s notion of the “development of doctrine,” which teaches that doctrine really can change. But that didn’t fit with the universal revelation that he was looking for in Catholicism. Nor did today’s conflict between liberal and conservative Catholics correspond with his ideal of a single, unified Magisterium. From the article