It is necessary to obey a Pope in all things as long as he does not go against the universal customs of the Church, but should he go against the universal customs of the Church, he need not be followed.

The 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.

Anyone who attempts to construe a personal view of God which conflicts with church dogma must be burned without pity.

We believe that the Greeks have been punished through [the Crusades] by the just judgement of God: these Greeks who have striven to rend the Seamless Robe of Jesus Christ ... Those who would not join Noah in his ark perished justly in the deluge; and these have justly suffered famine and hunger who would not receive as their shepherd the blessed Peter, Prince of the Apostles.

God forbid that all children, of whom daily so great a multitude die, would perish, but that also for these, the merciful God, who wishes no one to perish, has procured some remedy unto salvation.

If it shall be necessary, through sentences of excommunication against their persons and of interdict against their lands, all backsliding being put an end to, they compel them to fulfil their vows.

Every cleric must obey the Pope, even if he commands what is evil; for no one may judge the Pope.