Whether vainglory is a mortal sin?

❌ Objection 1 : It seems that vainglory is a mortal sin. For nothing precludes the eternal reward except a mortal sin. Now vainglory precludes the eternal reward: for it is written (Mt. 6:1): "Take heed, that you do not give justice before men, to be seen by them: otherwise you shall not have a reward of your Father Who is in heaven." Therefore vainglory is a mortal sin.

❌ Objection 2 : Further, whoever appropriates to himself that which is proper to God, sins mortally. Now by desiring vainglory, a man appropriates to himself that which is proper to God. For it is written (Is. 42:8): "I will not give My glory to another," and (1 Tim. 1:17): "To . . . the only God be honor and glory." Therefore vainglory is a mortal sin.

❌ Objection 3 : Further, apparently a sin is mortal if it be most dangerous and harmful. Now vainglory is a sin of this kind, because a gloss of Augustine on 1 Thess. 2:4, "God, Who proveth our hearts," says: "Unless a man war against the love of human glory he does not perceive its baneful power, for though it be easy for anyone not to desire praise as long as one does not get it, it is difficult not to take pleasure in it, when it is given." Chrysostom also says (Hom. xix in Matth.) that "vainglory enters secretly, and robs us insensibly of all our inward possessions." Therefore vainglory is a mortal sin.