The interpretation timeline
Galatians 6:15 Douay-Rheims

For in Christ Jesus neither circumcision availeth any thing, nor uncircumcision, but a new creature.

A.D. 407 – 1871 7 witnesses

Patristic

before A.D. 750
407
A.D.
John Chrysostom Patristic
A.D. 347–407
“"For neither is circumcision any thing, nor uncircumcision, but a new creature. And as many as shall walk by this rule, peace be upon them, and mercy, and upon the Israel of God." Observe the power of the Cross, to what a pitch it hath raised him! not only hath it put to death for him all mundane affairs, but hath set him far above the Old Dispensation. What can be comparable to this power? for the Cross hath persuaded him, who was willing to be slain and to slay others for the sake of circumcision, to leave it on a level with uncircumcision, and to seek for things strange and marvellous and above the heavens. This our rule of life he calls "a new creature," both on account of what is past, and of what is to come; of what is past, because our soul, which had grown old with the oldness of sin, hath been all at once renewed by baptism, as if it had been created again. Wherefore we require a new and heavenly rule of life. And of things to come, because both the heaven and the earth, and all the creation, shall with our bodies be translated into incorruption. Tell me not then, he says, of circumcision, which now availeth nothing; (for how shall it appear, when all things have undergone such a change?) but seek the new things of grace. For they who pursue these things shall enjoy peace and amity, and may properly be called by the name of "Israel." While they who hold contrary sentiments, although they be descended from him (Israel) and bear his appellation, have yet fallen away from all these things, both the relationship and the name itself. But it is in their power to be true Israelites, who keep this rule, who desist from the old ways, and follow after grace.”
Source

Scholastic

c. 1100 – 1500
1273
A.D.
Thomas Aquinas Catholic
1225–1274
“After the Apostle has explained the wicked intention of those who were seducing, here he intimates his own. And first he sets down his own intention; second, he shows the sign of this intention, at the words "by whom the world to me," etc.; third, he assigns the reason for his intention, at the words "in Christ Jesus," etc. He says therefore: the intention of those seducing is apparent, because they glory in the flesh, but I seek another glory, namely in the cross. And this is what he says: "God forbid that I should glory," etc. See that where the philosopher of the world blushed, there the Apostle found a treasure. What seemed folly to that one became wisdom and glory to the Apostle, as Augustine says. For each one glories in that thing by which he is reckoned great. Thus he who reckons himself great in riches glories in them, and so of the others. For he who reckons himself great in nothing else except in Christ, glories in Christ alone. Such, however, was the Apostle. Hence he said above, chapter 2, verse 20: "I live, now not I, but Christ truly lives in me." And therefore he glories in nothing but Christ, but especially in the cross of Christ, and this because in it are found all the things in which men are accustomed to glory. For some glory in the friendship of great men (say, of kings or princes): and this the Apostle found most of all in the cross, because there is shown an evident sign of divine friendship, Romans 5:8: "But God commends his charity in us," etc. For nothing so shows his charity toward us, as the death of Christ. Hence Gregory: "O inestimable love of charity. That you might redeem a slave, you handed over your Son." Likewise some glory in knowledge. And this the Apostle found more excellent in the cross. 1 Corinthians 2:2: "For I judged not myself to know anything among you, except Jesus Christ," etc. For in the cross is the perfection of the whole law, and the whole art of living well. Likewise some glory in power. And this the Apostle had to the greatest degree through the cross. 1 Corinthians 1:18: "The word of the cross is foolishness to those who perish, but to those who are being saved, that is, to us, it is the power of God." Likewise some glory in liberty obtained. And this the Apostle attained through the cross. Romans 6:6: "Our old man is crucified, that we may no longer serve sin." Likewise some glory in being taken up into some great college. But through the cross of Christ they are taken up into the heavenly college. Colossians 1:20: "Making peace through the blood of his cross, whether the things that are in the heavens, or the things that are on the earth." Likewise some glory in the triumphal sign of victory. But the cross is the triumphal sign of Christ's victory against the Demons. Colossians 2:15: "Despoiling the principalities and powers, he confidently led them away, openly triumphing over them," etc. Wisdom 14:7: "Blessed is the wood by which justice is done." He then adds the sign of his own intention, saying "by whom the world to me," etc. But because what he says, "God forbid that I should glory, save in the cross," etc., is an exceptive proposition, including one affirmative and another negative, therefore he sets down a twofold sign, proving each proposition. And first indeed he proves the negative, namely that he glories in nothing but the cross; and this, when he says "by whom the world is crucified to me," etc. For that in which someone glories is not dead in his heart, but rather that which he despises is. Psalm 30:13: "I am given over to oblivion like one dead from the heart." Now it is manifest that the world, and all the things that are in the world, were dead in the heart of Paul, Philippians 3:8: "I have reckoned all things as dung, that I may gain Christ." Therefore he does not glory in the world, nor in the things that are in the world, and this is what he says: truly I glory in nothing else, except in the cross of Christ, "by whom" — namely, by Christ crucified — "the world is crucified to me," that is, it is dead in my heart, so that I desire nothing in it. Second he proves the affirmative, namely that he glories in the cross of Christ, saying that he is crucified to the world. For he who glories in something, displays that in himself, and desires to make it manifest; but the Apostle displays nothing in himself, nor desires to make anything manifest, except what pertains to the cross of Christ, and therefore he glories only in it. And this is what he says: "and I to the world," namely, I am crucified; as if he were to say: I bear the insignia of the cross, and I am reckoned as dead. And therefore just as the world shudders at the cross of Christ, so it shudders at me. Colossians 3:3: "For you are dead, and your life is hidden with Christ in God," etc. But the reason why he does not glory in anything else, he shows by adding "for in Christ Jesus," etc. For indeed he glories most in that which avails and helps toward being joined to Christ, for this is what the Apostle desires, namely, to be with Christ. And because the Jewish rite does not avail for this, nor the observance of the Gentiles, but the cross of Christ alone, therefore he glories only in it. And this is what he says: "in Christ neither circumcision avails anything" — that is, the Jewish rite — "nor uncircumcision" — that is, the observance of the Gentiles — that is, for justifying and joining to Christ, "but a new creature" avails for this. This indeed is clear from what was said above at verse 6 (in almost the same words): "For in Christ Jesus neither circumcision avails anything, nor uncircumcision, but faith which works through love." Faith, therefore, formed by charity, is the new creature. For we were created and brought forth into the being of nature through Adam; but that creature indeed was already old, and grown old, and therefore the Lord, bringing us forth, and establishing us in the being of grace, made a certain new creature. James 1:18: "That we may be some beginning of his creature." And it is called new, because through it we are renewed unto a new life; and through the Holy Spirit, Psalm 103:30: "Send forth your Spirit, and they shall be created, and you shall renew the face of the earth." And through the cross of Christ, 2 Corinthians 5:17: "If there be any new creature in Christ," etc. Thus therefore through the new creature, namely through faith in Christ and the charity of God, which is poured forth in our hearts, we are renewed, and joined to Christ.”

Reformation

c. 1500 – 1650
1637
A.D.
1567–1637
“In Christ Jesus neither circumcision availeth anything . Whether you be Jew or Gentile matters nothing ; neither brings you nearer Christ. What is of importance is a new creature, i.e., a soul regenerated in baptism, and fortified by grace to walk in newness of life. CC Rev. iii. 14, where Christ is called “the beginning of the creation of God,” and Isa. ix. 6, where He is called “the Father of the world that is to be” (Vulg.), for from Him began a new creation. Cf. too Virgil (Eel. iv. 8), where Virgil transfers to Salonius, the newly born son of Asinius Poliio, Roman Consul, the predictions by the Cumaean Sibyl of the birth of Christ, in which the Christian era is described as a golden age. Ver. 6 . — And as many as walk according to this rule. The rule laid down by S. Paul as to justification, and the relation of Judaism to Christianity. Peace be on them , and mercy , and upon the Israel of God. On Jews and Gentiles alike who believe on Christ, according to Ambrose ; but comparing this verse with Eph. i. 1 and Col ii. 8, it is better to explain the Israel of God as those who are Israelites indeed, i.e., who have embraced Christianity and renounced whether Gentilism or Judaism. Not those who are descended from Jacob according to the flesh are the Israel of God, but those who have STIGMATA 345 embraced his faith. These find peace within, and on them God plentifully bestows His grace. There may be a reference to the meaning of Israel, i.e. y he who sees God, says Theophylact They who see Him by faith here will see Him under a fitting image in heaven. Or Israel may mean “he who has power with God,” according to Gen. xxxii. 28. As Jacob by his prayers obtained success against Esau, so the people of God are by His grace masters over the world and all its lusts, and over Judaism. So S. Thomas and Haymo”
Source

Post-Reformation

c. 1650 – 1900
1771
A.D.
John Gill Reformed
1697–1771
“And as many as walk according to this rule,.... Or canon; meaning not the canon of the Scriptures in general, which is the perfect rule, and only standard of faith and practice; according to which we are to walk, believe, and act; but either the doctrine of justification by the righteousness of Christ, the subject of this epistle, the truth the apostle had been explaining, vindicating, and confirming; and which to depart from, is going out of the way of truth; and an abiding by it, is walking in it; and is a good rule and standard, by which to distinguish between truth and error; for whatever is contrary to that article of faith cannot be true: or else the rule delivered in the preceding verse, declaring circumcision and uncircumcision to be of no avail in salvation, but a new creature; and to walk according to this rule, is to renounce all trust in, and dependence upon any outward things; to believe alone in Christ, for righteousness and life; to live by faith upon him, and to walk in newness of life, under the influences of his Spirit and grace: peace be on them, and mercy. This is the apostle's godly wish, unfeigned desire, and hearty prayer for all such persons, be they who they will; Jews or Gentiles, circumcised or uncircumcised: by peace he means, a view of their peace with God, made by the blood of Christ; peace in their own consciences, which passes all understanding, and arises from a comfortable sense of justification by the righteousness of Christ, of pardon by his blood, and atonement by his sacrifice; and which is enjoyed in a way of believing; and also peace with one another, among themselves as brethren, which is a very desirable blessing: in short, it includes all prosperity and happiness, inward and outward, temporal, spiritual, and eternal: and by "mercy", he designs the love and grace of God, to sinful miserable creatures in themselves, which is the spring and fountain of all peace and prosperity; and which is displayed in the covenant of grace, and all the blessings of it; in the mission and incarnation of Christ, and redemption by him; in regeneration, forgiveness of sin, and complete salvation; and intends a fresh discovery, manifestation, and application of the mercy of God to his children; who often stand in need thereof, being distressed with the guilt of sin, or are under desertions or afflictive providences, at which time to have mercy showed them, is exceeding suitable and agreeable: when the apostle wishes these to be "on" them, it signifies that these blessings come from above, as every good gift does; that they descend as a cloud, and rest upon them, and abide with them, refreshing, comforting, and protecting them: he adds, and upon the Israel of God; which is a further description of the persons, for whom he prays for these blessings; and is not to be understood by way of distinction from them, but as an amplification of their character; and as pointing out the Israel, by way of emphasis, the Israel, or Israelites indeed, the spiritual Israel, as distinct from Israel according to the flesh; see Co1 10:18. The "Israel of God", or as the Arabic version reads it, "Israel the propriety of God"; which he has a right unto, and a claim upon; who are chosen by him, Israel his elect; who are redeemed by him, out of every kindred, tongue, people, and nation; who are called by his grace, and are styled Israel his called; who are justified in his Son, and by his righteousness; and for whose sake he is exalted as a Prince and a Saviour, to give them repentance and remission of sin; and who are, or will be saved by him, with an everlasting salvation; and is a name that includes all God's elect, whether Jews or Gentiles: though it may have a particular respect to such of the Israelites, or Jews, God had foreknown and reserved for himself; and who believed in Christ, and walked as new creatures, without confidence in the flesh. The Jews themselves own, that strangers, or proselytes, shall be called by the name of Israel; so they (b) explain Isa 44:5, latter part. (b) Jarchi & Abarbinel in Isa. xliv. 5.”
Source
1832
A.D.
Adam Clarke Methodist
1762–1832
“In Christ Jesus - Under the dispensation of the Gospel, of which he is head and supreme, neither circumcision - nothing that the Jew can boast of, nothing that the Gentile can call excellent, availeth any thing - can in the least contribute to the salvation of the soul. But a new creature - Αλλα καινη κτισις· But a new creation; not a new creature merely, (for this might be restrained to any new power or faculty), but a total renewal of the whole man, of all the powers and passions of the soul; and as creation could not be effected but by the power of the Almighty, so this change cannot be effected but by the same energy; no circumcision can do this; only the power that made the man at first can new make him. See the note on Co1 7:19, and on Co2 5:17 (note).”
Source
1849
A.D.
1774–1849
“But a new creature; but to be born anew, to receive the spiritual life of grace. (Witham)”
1871
A.D.
1871
“availeth--The oldest manuscripts read, "is" (compare Gal 5:6). Not only are they of no avail, but they are nothing. So far are they from being matter for "glorying," that they are "nothing." But Christ's cross is "all in all," as a subject for glorying, in "the new creature" (Eph 2:10, Eph 2:15-16). new creature-- (Co2 5:17). A transformation by the renewal of the mind (Rom 12:2).”
Source
Modern · 1953 →

The in-app commentary runs from the Fathers to the early-modern record, then stops — that's where the public-domain sources end, not where the reading does. For the modern reading, follow the sources directly.