Objection 1. It seems that circumcision did not bestow sanctifying grace. For the Apostle says (Galatians 2:21): "If justice be by the Law, then Christ died in vain," i.e. without cause. But circumcision was an obligation imposed by the Law, according to Galatians 5:3: "I testify... to every man circumcising himself, that ne is a debtor to do the whole law." Therefore, if justice be by circumcision, "Christ died in vain," i.e. without cause. But this cannot be allowed. Therefore circumcision did not confer grace whereby the sinner is made righteous.
Objection 2. Further, before the institution of circumcision faith alone sufficed for justification; hence Gregory says (Moral. iv): "Faith alone did of old in behalf of infants that for which the water of Baptism avails with us." But faith has lost nothing of its strength through the commandment of circumcision. Therefore faith alone justified little ones, and not circumcision.
Objection 3. Further, we read (Joshua 5:5-6) that "the people that were born in the desert, during the forty years... were uncircumcised." If, therefore, original sin was taken away by circumcision, it seems that all who died in the desert, both little children and adults, were lost. And the same argument avails in regard to those who died before the eighth day, which was that of circumcision, which day could nol be anticipated, as stated above (3, ad 3).
Objection 4. Further, nothing but sin closes the entrance to the heavenly kingdom. But before the Passion the entrance to the heavenly kingdom was closed to the circumcised. Therefore men were not justified from sin by circumcision.
Objection 5. Further, original sin is not remitted without actual sin being remitted also: because "it is wicked to hope for half forgiveness from God," as Augustine says (De Vera et Falsa Poenit. ix). But we read nowhere of circumcision as remitting actual sin. Therefore neither did it remit original sin.
On the contrary, Augustine says, writing to Valerius in answer to Julian (De Nup. et Concup. i.): "From the time that circumcision was instituted among God's people, as 'a seal of the justice of the faith,' it availed little children unto sanctification by cleansing them from the original and bygone sin; just as Baptism also from the time of its institution began to avail unto the renewal of man."
I answer that, All are agreed in saying that original sin was remitted in circumcision. But some said that no grace was conferred, and that the only effect was to remit sin. The Master holds this opinion (Sent. iv, D, 1), and in a gloss on Romans 4:11. But this is impossible, since guilt is not remitted except by grace, according to Romans 3:2: "Being justified freely by His grace," etc.
Wherefore others said that grace was bestowed by circumcision, as to that effect which is the remission of guilt, but not as to its positive effects; lest they should be compelled to say that the grace bestowed in circumcision sufficed for the fulfilling of the precepts of the Law, and that, consequently, the coming of Christ was unnecessary. But neither can this opinion stand. First, because by circumcision children. received the power of obtaining glory at the allotted time, which is the last positive effect of grace. Secondly, because, in the order of the formal cause, positive effects naturally precede those that denote privation, although it is the reverse in the order of the material cause: since a form does not remove a privation save by informing the subject.
Consequently, others said that grace was conferred in circumcision, also as a particular positive effect consisting in being made worthy of eternal life; but not as to all its effects, for it did not suffice for the repression of the concupiscence of the fomes, nor again for the fulfilment of the precepts of the Law. And this was my opinion at one time (Sent. iv, D, 1; 2, 4). But if one consider the matter carefully, it is clear that this is not true. Because the least grace can resist any degree of concupiscence, and avoid every mortal sin, that is committed in transgressing the precepts of the Law; for the smallest degree of charity loves God more than cupidity loves "thousands of gold and silver" (Psalm 118:72).
We must say, therefore, that grace was bestowed in circumcision as to all the effects of grace, but not as in Baptism. Because in Baptism grace is bestowed by the very power of Baptism itself, which power Baptism has as the instrument of Christ's Passion already consummated. Whereas circumcision bestowed grace, inasmuch as it was a sign of faith in Christ's future Passion: so that the man who was circumcised, professed to embrace that faith; whether, being an adult, he made profession for himself, or, being a child, someone else made profession for him. Hence, too, the Apostle says (Romans 4:11), that Abraham "received the sign of circumcision, a seal of the justice of the faith": because, to wit, justice was of faith signified: not of circumcision signifying. And since Baptism operates instrumentally by the power of Christ's Passion, whereas circumcision does not, therefore Baptism imprints a character that incorporates man in Christ, and bestows grace more copiously than does circumcision; since greater is the effect of a thing already present, than of the hope thereof.
Reply to Objection 1. This argument would prove if justice were of circumcision otherwise than through faith in Christ's Passion.
Reply to Objection 2. Just as before the institution of circumcision, faith in Christ to come justified both children and adults, so, too, after its institution. But before, there was no need of a sign expressive of this faith; because as yet believers had not begun to be united together apart from unbelievers for the worship of one God. It is probable, however, that parents who were believers offered up some prayers to God for their children, especially if these were in any danger. Or bestowed some blessing on them, as a "seal of faith"; just as the adults offered prayers and sacrifices for themselves.
Reply to Objection 3. There was an excuse for the people in the desert failing to fulfil the precept of circumcision, both because they knew not when the camp was removed, and because, as Damascene says (De Fide Orth. iv) they needed no distinctive sign while they dwelt apart from other nations. Nevertheless, as Augustine says (QQ. in Josue vi), those were guilty of disobedience who failed to obey through contempt.
It seems, however, that none of the uncircumcised died in the desert, for it is written (Psalm 104:37): "There was not among their tribes one that was feeble": and that those alone died in the desert, who had been circumcised in Egypt. If, however, some of the uncircumcised did die there, the same applies to them as to those who died before the institution of circumcision. And this applies also to those children who, at the time of the Law, died before the eighth day.
Reply to Objection 4. Original sin was taken away in circumcision, in regard to the person; but on the part of the entire nature, there remained the obstacle to the entrance of the kingdom of heaven, which obstacle was removed by Christ's Passion. Consequently, before Christ's Passion not even Baptism gave entrance to the kingdom. But were circumcision to avail after Christ's Passion, it would give entrance to the kingdom.
Reply to Objection 5. When adults were circumcised, they received remission not only of original, but also of actual sin: yet not so as to be delivered from all debt of punishment, as in Baptism, in which grace is conferred more copiously.
Source: Summa Theologica (New Advent)