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.

Obj. 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.

Obj. 3: Further, the greater sin deserves the greater punishment,
according to Deut. 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.

_On the contrary,_ Augustine, commenting on John 15:22, "If I had not
come, and spoken to them, they would not have sin," says (Tract.
lxxxix in Joan.): "Under the general name, He refers to a singularly
great sin. For this," viz. infidelity, "is the sin to which all others
may be traced." Therefore unbelief is the greatest of sins.

_I answer that,_ Every sin consists formally in aversion from God, as
stated above (I-II, Q. 71, A. 6; I-II, Q. 73, A. 3). Hence the more a
sin severs man from God, the graver it is. Now man is more than ever
separated from God by unbelief, because he has not even true
knowledge of God: and by false knowledge of God, man does not
approach Him, but is severed from Him.

Nor is it possible for one who has a false opinion of God, to know
Him in any way at all, because the object of his opinion is not God.
Therefore it is clear that the sin of unbelief is greater than any
sin that occurs in the perversion of morals. This does not apply to
the sins that are opposed to the theological virtues, as we shall
state further on (Q. 20, A. 3; Q. 34, A. 2, ad 2; Q. 39, A. 2, ad 3).

Reply Obj. 1: Nothing hinders a sin that is more grave in its genus
from being less grave in respect of some circumstances. Hence
Augustine hesitated to decide between a bad Catholic, and a heretic
not sinning otherwise, because althou