Whether fornication is the most grievous of sins?

❌ Objection 1 : It would seem that fornication is the most grievous of sins. For seemingly a sin is the more grievous according as it proceeds from a greater sensuous pleasure. Now the greatest sensuous pleasure is in fornication, for a gloss on 1 Cor. 7:9 says that the "flame of sensuous pleasure is most fierce in lust." Therefore it seems that fornication is the gravest of sins.

❌ Objection 2 : Further, a sin is the more grievous that is committed against a person more closely united to the sinner: thus he sins more grievously who strikes his father than one who strikes a stranger. Now according to 1 Cor. 6:18, "He that committeth fornication sinneth against his own body," which is most intimately connected with a man. Therefore it seems that fornication is the most grievous of sins.

❌ Objection 3 : Further, the greater a good is, the graver would seem to be the sin committed against it. Now the sin of fornication is seemingly opposed to the good of the whole human race, as appears from what was said in the foregoing Article. It is also against Christ, according to 1 Cor. 6:15, "Shall I . . . take the members of Christ, and make them the members of a harlot?" Therefore fornication is the most grievous of sins.