This is a good example of a false faith; you claim you bought into it, yet you walked away from it, so you were never wholly convinced because if you had been you would have persevered; likewise people claim to have faith in Jesus and even participate with and hang around with like-minded people, only to later decide it isn’t right and they do not believe it so they turn around. True faith is true faith because it perseveres; it is its character to do so, whatever the faith. We take your word that you have true faith in the Catholic magisterium because by your actions you demonstrate it, but if you later change your mind and turn around, although you participated in everything Catholic, your faith was not real.
This is just a hypothetical ting here to demonstrate that real faith perseveres by its very nature, which is why people that claim to have faith in Christ and later walk away never had a true faith to begin with or they believed it was true until they found more information and decided …nahhww I don’t believe this or want anything to do with this; this is why John stated "They went out from us, but they were not {really} of us; for if they had been of us, they would have remained with us; but {they went out,} so that it would be shown that they all are not of us." - the word remain is the key word that is the perseverance characteristic of a true faith in whatever one claims to have faith in.
Just like it takes great faith to believe Mary gave birth to God, not to mention the implication of such a statement, when by His very nature God has always existed and actually created Mary, the channel He used to reveal Himself in the Person of Jesus. The reason Scripture specifically states He is in the “likeness of human flesh” is because of the birth; so to answer Benedict; yes every mother give birth to a little sinner, which is their nature. Whereas Jesus was born in the “likeness of human flesh” because He is without a sin nature. It is a little hard to wrap a mind around because we are so limited in our understanding in comparison to Gods.