Whether it is permissible to receive communion from heretical, excommunicate, or sinful priests, and to hear mass said by them?

❌ Objection 1 : It seems that one may lawfully receive Communion from heretical, excommunicate, or even sinful priests, and to hear mass said by them. Because, as Augustine says (Contra Petilian. iii), "we should not avoid God's sacraments, whether they be given by a good man or by a wicked one." But priests, even if they be sinful, or heretics, or excommunicate, perform a valid sacrament. Therefore it seems that one ought not to refrain from receiving Communion at their hands, or from hearing their mass.

❌ Objection 2 : Further, Christ's true body is figurative of His mystical body, as was said above (Question [67], Article [2]). But Christ's true body is consecrated by the priests mentioned above. Therefore it seems that whoever belongs to His mystical body can communicate in their sacrifices.

❌ Objection 3 : Further, there are many sins graver than fornication. But it is not forbidden to hear the masses of priests who sin otherwise. Therefore, it ought not to be forbidden to hear the masses of priests guilty of this sin.