I answer that, Punishment is proportionate to sin.  Now sin comprises two things.  First, there is the turning away from the immutable good, which is infinite, wherefore, in this respect, sin is infinite.  Secondly, there is the inordinate turning to mutable good.  In this respect sin is finite, both because the mutable good itself is finite, and because the movement of turning towards it is finite, since the acts of a creature cannot be infinite.  Accordingly, in so far as sin consists in turning away from something, its corresponding punishment is the pain of loss, which also is infinite, because it is the loss of the infinite good, i.e.  God.  But in so far as sin turns inordinately to something, its corresponding punishment is the pain of sense, which is also finite.

Reply Obj. 1:  It would be inconsistent with Divine justice for the sinner to be brought to nothing absolutely, because this would be incompatible with the perpetuity of punishment that Divine justice requires, as stated above (A. 3).  The expression “to be brought to nothing” is applied to one who is deprived of spiritual goods, according to 1 Cor. 13:2:  “If I . . . have not charity, I am nothing.”

Reply Obj. 2:  This argument considers sin as turning away from something, for it is thus that man sins against God.

Reply Obj. 3:  Duration of punishment corresponds to duration of fault, not indeed as regards the act, but on the part of the stain, for as long as this remains, the debt of punishment remains.  But punishment corresponds to fault in the point of severity.  And a fault which is irreparable, is such that, of itself, it lasts for ever; wherefore it incurs an everlasting punishment.  But it is not infinite as regards the thing it turns to; wherefore, in this respect, it does not incur punishment of infinite quantity. ________________________

FIFTH ARTICLE [I-II, Q. 87, Art. 5]

Whether Every Sin Incurs a Debt of Eternal Punishment?

Objection 1:  It would seem that every sin incurs a debt of eternal punishment.  Because punishment, as stated above (A. 4), is proportionate to the fault.  Now eternal punishment differs infinitely from temporal punishment:  whereas no sin, apparently, differs infinitely from another, since every sin is a human act, which cannot be infinite.  Since therefore some sins incur a debt of everlasting punishment, as stated above (A. 4), it seems that no sin incurs a debt of mere temporal punishment.

Obj. 2:  Further, original sin is the least of all sins, wherefore Augustine says (Enchiridion xciii) that “the lightest punishment is incurred by those who are punished for original sin alone.”  But original sin incurs everlasting punishment, since children who have died in original sin through not being baptized, will never see the kingdom of God, as shown by our Lord’s words (John 3:3):  “Unless a man be born again, he cannot see the kingdom of God.”  Much more, therefore, will the punishments of all other sins be everlasting.