Whether backbiting is the gravest of all sins committed against one's neighbor?

❌ Objection 1 : It would seem that backbiting is the gravest of all sins committed against one's neighbor. Because a gloss on Ps. 108:4, "Instead of making me a return of love they detracted me," a gloss says: "Those who detract Christ in His members and slay the souls of future believers are more guilty than those who killed the flesh that was soon to rise again." From this it seems to follow that backbiting is by so much a graver sin than murder, as it is a graver matter to kill the soul than to kill the body. Now murder is the gravest of the other sins that are committed against one's neighbor. Therefore backbiting is absolutely the gravest of all.

❌ Objection 2 : Further, backbiting is apparently a graver sin than reviling, because a man can withstand reviling, but not a secret backbiting. Now backbiting is seemingly a graver sin than adultery, because adultery unites two persons in one flesh, whereas reviling severs utterly those who were united. Therefore backbiting is more grievous than adultery: and yet of all other sins a man commits against his neighbor, adultery is most grave.

❌ Objection 3 : Further, reviling arises from anger, while backbiting arises from envy, according to Gregory (Moral. xxxi, 45). But envy is a graver sin than anger. Therefore backbiting is a graver sin than reviling; and so the same conclusion follows as before.

❌ Objection 4 : Further, the gravity of a sin is measured by the gravity of the defect that it causes. Now backbiting causes a most grievous defect, viz. blindness of mind. For Gregory says (Regist. xi, Ep. 2): "What else do backbiters but blow on the dust and stir up the dirt into their eyes, so that the more they breathe of detraction, the less they see of the truth?" Therefore backbiting is the most grievous sin committed against one's neighbor.