Whether unbelief is the greatest of sin?

❌ Objection 1 : It would seem that unbelief is not the greatest of sins. For Augustine says (De Bapt. contra Donat. iv, 20): "I should hesitate to decide whether a very wicked Catholic ought to be preferred to a heretic, in whose life one finds nothing reprehensible beyond the fact that he is a heretic." But a heretic is an unbeliever. Therefore we ought not to say absolutely that unbelief is the greatest of sins.

❌ Objection 2 : Further, that which diminishes or excuses a sin is not, seemingly, the greatest of sins. Now unbelief excuses or diminishes sin: for the Apostle says (1 Tim. 1:12,13): "I . . . before was a blasphemer, and a persecutor and contumelious; but I obtained . . . mercy . . . because I did it ignorantly in unbelief." Therefore unbelief is not the greatest of sins.

❌ Objection 3 : Further, the greater sin deserves the greater punishment, according to Dt. 25:2: "According to the measure of the sin shall the measure also of the stripes be." Now a greater punishment is due to believers than to unbelievers, according to Heb. 10:29: "How much more, do you think, he deserveth worse punishments, who hath trodden under foot the Son of God, and hath esteemed the blood of the testament unclean, by which he was sanctified?" Therefore unbelief is not the greatest of sins.