Because few Catholics are bold enough to say they actually know all the Church’s teachings, the traditional recourse is some version of “the Church cannot err in its teaching, so whatever she teaches—even if I’m still struggling with, or even unaware of, that teaching—must be true.” But of course the Church teaches via her bishops, and preeminently the bishop of Rome. So the claim is, in effect, “I trust that the bishops and the pope speak the truth.” (Yes, I’m aware that the underlying theological claim is a little more sophisticated than that; still.)
But that trust is precisely what is being forfeited with the cover-up scandals. And note the already evident domino effect. In light of the scandals, many faithful Catholics, for example, are now comfortable saying that it was likely a mistake to canonize John Paul II. But it has long been the majority opinion of the Church’s theologians that canonizations are exercises of papal infallibility. If, in light of the scandals, otherwise faithful Catholics are now willing to doubt what was long believed an infallible exercise of magisterial authority, there’s little reason for them not to doubt other of the Church’s teachings. That’s not to say they necessarily will doubt other teachings; but the door’s been cracked and there’s no longer a principle to prevent it being thrown wide open.
h/t D.G. Hart.