You don't remember this thread?
....One remark his wife makes in this book suggests that Hahn's desire to be noticed is great: "Scott suffered tremendous loneliness. He was misunderstood and rejected by many Protestant friends who didn't want to talk to him.... He felt that former professors didn't think he was worth pursuing to convince him he was wrong [about Scripture]. And he couldn't understand the nonchalance of a number of [Roman] Catholics at Marquette [University, where Hahn was a student at the time] over his conversion, acting rather hohum over the whole thing, rather than welcoming him for all he had risked and left behind" (109). What good is being a martyr if no one notices you?........As for [Hahn's wife] Kimberly, "At this point [more than halfway through seminary] I was not steeped in Reformation theology, so the change in how I viewed justification did not seem momentous" . Please consider the import of that statement. Here are two graduates of a Presbyterian College, two students nearing completion of their studies at reputedly one of the best evangelical Protestant seminaries in the country, two professing Christians – and the meaning of justification is not all that important to them. As we shall soon see, despite – or rather because of – their education, the Hahns – especially Scott – could not defend the Reformation principles of the Bible alone, faith alone, and Christ alone....
-- From the thread The Lost Soul of Scott Hahn
Here are two graduates of a Presbyterian College, two students nearing completion of their studies at reputedly one of the best evangelical Protestant seminaries in the country, two professing Christians – and the meaning of justification is not all that important to them.
*If* that were true, that's an indictment of Calvinist, Presbyterian Protestantism, and of "one of the best evangelical Protestant seminaries in the country".
Except that it isn't. Scott, not Kimberly, is crystal clear that he was gung-ho for the Lutheran/Calvinist understanding of justification, until he got to Protestant, Calvinist seminary and discovered that the arguments against it were strong. (He's not alone in this. Heard of the "New Perspective on Paul"?)
Discovering that something is wrong, and that you were mistaken to believe in it, is not always the same thing as being ignorant about it.
Were it so, we could conclude quite easily that all of those ex-Catholics who become Protestants are prima facie ignorant of Catholicism. (I happen to think that a great many are, but I don't think it's a given by implication.)