Not to oppose erroneous doctrine is to approve of it, and not to defend at all true doctrine is to suppress it.
Pope Innocent IIIThe Jews' guilt of the crucifixion of Jesus consigned them to perpetual servitude, and, like Cain, they are to be wanderers and fugitives. The Jews will not dare to raise their necks, bowed under the yoke of perpetual slavery, against the reverence of the Christian faith.
Pope Innocent IIIThe Pope should not flatter himself about his power nor should he rashly glory in his honor and high estate, because the less he is judged by man, the more he is judged by God. Still the less can the Roman Pontiff glory because he can be judged by men, or rather, can be shown to be already judged, if for example he should wither away into heresy; because he who does not believe is already judged, In such a case it should be said of him: 'If salt should lose its savor, it is good for nothing but to be cast out and trampled under foot by men.'
Pope Innocent IIIThe mysteries of the faith are not to [be] explained rashly to anyone. Usually in fact, they cannot be understood by everyone but only by those who are qualified to understand them with informed intelligence. The depth of the divine Scriptures is such that not only the illiterate and uninitiated have difficulty understanding them, but also the educated and the gifted.
Pope Innocent III