I had this book called "Phillip Birnbaum's Book of Jewish Concepts." And in the book he talks about a convert away from Judaism and goes on to say, ".... what vile being forsakes the religion of his youth to follow another...." Now wait a minute.
When non-Jews convert to Judaism, that's frequently protrayed as deep and holy and due to much critical reflection.
When I converted (I don't believe in Xianity anymore though) I had a lot of issues to contend with.
What does a 12 year old know about the world really? It's only when you really start to work and come in contact with the outside world that you start to formulate your basic principles of life, at least that's how it worked for me.
Even in the world of the University, you're still in the domain of theory not what's used in practice. I think Birnbaum is very harsh of people not like himself. And I think that's a trait of people who lead a life detached from reality because they're in the academic world. And Judaism is very much a religion of book knowledge.