Is it possible for a married Catholic to be invincibly ignorant that adultery is gravely wrong? Is it possible for a married Catholic to be invincibly ignorant that adultery is gravely wrong? I am interested in an answer from the Catholic viewpoint.
A (validly) married Catholic cannot be invincibly ignorant of the sinfulness of adultery because marriage consent, &quot;the efficient cause of matrimony&quot; (Summa Theologica suppl. q. 45 a. 1), is consent to &quot;the union of persons directed to one purpose&quot; (ibid. ad 2; cf. q. 44 a. 1), or as Canon Law expresses it:

1917 CIC 1081 (1983 CIC 1057)

Matrimonial consent is an act of the will by which each party gives and accepts perpetual and exclusive rights to the body, for those actions that are of themselves suitable for the generation of children.


Regarding ignorance:

1917 CIC 1082 (1983 CIC 1096)

In order that matrimonial consent be considered [valid], it is necessary that the contractants at least not be ignorant that marriage is a permanent society between a man and woman for the procreation of children.

This ignorance is not presumed after puberty.



cf. Summa Theologica II-II q. 154 a. 2 &quot;Whether simple fornication is a mortal sin?&quot;