[De communione et conversatione Iudaeorum et Christianorum]

Blessed Paul also says in his first letter to the Corinthians, chapter 10. He provides two cases in which it was permitted to eat food sacrificed to idols. First, when it was not known that it was sacrificed to idols. Second, when it does not scandalize the neighbor, as the text says: "All things are lawful for me, but not all things are expedient; all things are lawful for me, but not all things edify. Let no man seek his own, but that which is another's. Whatsoever is sold in the shambles, that eat, asking nothing for conscience' sake. For the earth is the Lord's and the fulness thereof. If any of the infidels call you to a feast, and you be disposed to go, whatsoever is set before you, eat, asking no question for conscience' sake. But if any man say, This is offered in sacrifice unto idols, eat not for his sake that shewed it, and for conscience' sake," that is, of the other. The gloss says, lest he believe you are eating with reverence for the idol and glory in his superstition, not because the food is unclean. And although there was contention in the primitive Church between the communion of Gentiles and Jews, because Jews discern foods and Gentiles do not, today, however, the gloss (c. "Quod sit laudabilis") says: "If these and those discern our foods, therefore we do not commune with them at the table, nor they with us, unless in the manner stated." Wherefore, it is holier to die than to eat idol-sacrificed food with reverence for an idol. Blessed Augustine says this in On the Good of Marriage, and the canon (28, q. 3, c. "Sicut sanctius") adopts it. Yet the gloss says that in extreme necessity, one could eat idol-sacrificed food with a renunciation of the idol, because necessity has no law (de cons., dist. 1, "Sicut"). Just as due to the necessity of hunger, it is permitted to take the property of others, to omit homicide, and to eat meat during Lent. Also, it is said that communion with them is forbidden because they have nothing except through usury and the blood of the poor, which they are bound to restore. Therefore, they consume the society of others; hence, the more powerful ones must return it to restitution.

The third admonition: No Christian should mix with any Jewish woman, or any Christian woman with any Jew, in carnal consort or commerce, under pain of excommunication. The canon (28, q. 1, c. "Si quis iudaice pravitati") establishes this. Similarly, if a marriage is contracted, marriage is forbidden between them because of the difference of religion (Exodus 34, Deuteronomy 7, and in the canon where above, c. "Iudaeorum" and c. "Cave").