The following was retrieved from the on-line Catholic Encyclopedia
(www.newadvent.org) and other Internet sources:

St. Augustine

“Had I been a Jew in the time of that ancient people, when there was nothing better that I could be, I would undoubtedly have received circumcision. That “seal of the righteousness which is by faith” was of so great importance in that dispensation before it was abrogated by the Lord’s coming, that the angel would have strangled the infant-child of Moses, had not the child’s mother, seizing a stone, circumcised the child, and by this sacrament averted impending deaths This sacrament also arrested the waters of the Jordan, and made them flow back towards their source. This sacrament the Lord Himself received in infancy, although He abrogated it when He was crucified. For these signs of spiritual blessings were not condemned, but gave place to others which were more suitable to the later dispensation. For as circumcision was abolished by the first coming of the Lord, so baptism shall be abolished by His second coming. For as now, since the liberty of faith has come, and the yoke of bondage has been removed, no Christian receives circumcision in the flesh; so then, when the just are reigning with the Lord, and the wicked have been condemned, no one shall be baptized, but the reality which both ordinances prefigure — namely, circumcision of the heart and cleansing of the conscience- shall be eternally abiding.” — St. Augustine to Maximin, Letter 23 (AD 392)

St. John Chrysostom

Commentary on Galatians

CHAPTER V

Ver. 2. “Behold, I Paul say unto you, that if ye receive circumcision, Christ will profit you nothing.”

Lo, what a threat! Reasonably then did he anathematize even angels. How then shall Christ profit them nothing? For he has not supported this by argument, but only declared it, the credence due to his authority, compensating, as it were, for all subsequent proof Wherefore he sets out by saying, “Behold, I Paul say unto you,” which is the expression of one who has confidence in what he asserts. We will subjoin what we can ourselves as to how Christ shall profit nothing them who are circumcised

Ver. 6. “For in Jesus Christ neither circumcision availeth any thing, nor uncircumcision; but faith working through love.”

Observe the great boldness with which he now encounters them; Let him that hath put on Christ, he says, no longer be careful about such matters. Having before said that Circumcision was hurtful, how is it that he now considers it indifferent? It is indifferent as to those who bad it previously to the Faith, but not as to those who are circumcised after the Faith was given. Observe too the view in which he places it, by setting it by the side of Uncircumcision; it is Faith that makes the difference. As in the selection of wrestlers, whether they be hook-nosed or flat-nosed, black or white, is of no importance in their trial, it is only necessary to seek that they be strong and skilful; so all these bodily accidents do not injure one who is to be enrolled under the New Covenant, nor does their presence assist him.

St. Thomas…

holds that circumcision was a figure of baptism: this retrenches and restrains the animal man as that removed a part of his body — which physical act indicated the spiritual effect of the sacrament (De Sac., Summa, III, Q. lxx, a. 1). He gives three reasons why the organ of generation rather than any other was to be circumcised:

Abraham was to be blessed in his seed;
The rite was to take away original sin, which comes by generation;
It was to restrain concupiscence, which is found especially in the generative organs (III, Q. lxx, a. 3).
St. Cyprian: In respect of the case of infants, which you say ought not to be baptized within the second or third day after birth, and that the law of ancient circumcision should be regarded, so that you think that one who is just born should not be baptized and sanctified within the eighth day, we all thought very differently in our council. For in this course which you thought was to be taken, no one agreed; but we all rather judge that the mercy and grace of God is not to be refused to any one born of man… Spiritual circumcision ought not to be hindered by carnal circumcision… we ought to shrink from hindering an infant, who, being lately born, has not sinned, except in that, being born after the flesh according to Adam, he has contracted the contagion of the ancient death at its earliest birth, who approaches the more easily on this very account to the reception of the forgiveness of sins – that to him are remitted, not his own sins, but the sins of another” (Letter 58 to Fidus).

St. Justin Martyr – Dialogue with Trypho (Between 138A.D. and 161 A.D.)

We too, would observe your circumcision of the flesh, your Sabbath days, and in a word, all you festivals, if we were not aware of the reason why they were imposed upon you, namely, because of your sins and the hardness of heart.

The custom of circumcising the flesh, handed down from Abraham, was given to you as a distinguishing mark, to set you off from other nations and from us Christians. The purpose of this was that you and only you might suffer the afflictions that are now justly yours; that only your land be desolated, and you cities ruined by fire, that the fruits of you land be eaten by strangers before your very eyes; that not one of you be permitted to enter your city of Jerusalem. Your circumcision of the flesh is the only mark by which you can certainly be distinguished from other men…as I stated before it was by reason of your sins and the sins of your fathers that, among other precepts, God imposed upon you the observance of the sabbath as a mark.