The interpretation timeline
2 Corinthians 1:21 Douay-Rheims

Now he that confirmeth us with you in Christ, and that hath anointed us, is God:

A.D. 99 – 1871 9 witnesses 10 excerpts

Patristic

before A.D. 750
99
A.D.
Clement of Rome Patristic
d. A.D. 99
“For this reason righteousness and peace are now far departed from you, inasmuch as every one abandons the fear of God, and has become blind in His faith, neither walks in the ordinances of His appointment, nor acts a part becoming a Christian, but walks after his own wicked lusts, resuming the practice of an unrighteous and ungodly envy, by which death itself entered into the world. [Wisdom 2:24]”
Source
220
A.D.
Tertullian Patristic
c. A.D. 150–220
“But if repentance is a thing human, its baptism must necessarily be of the same nature: else, if it had been celestial, it would have given both the Holy Spirit and remission of sins. But none either pardons sins or freely grants the Spirit save God only. Even the Lord Himself said that the Spirit would not descend on any other condition, but that He should first ascend to the Father.”
Source
397
A.D.
Ambrose of Milan Patristic
A.D. 339–397
“Having received the sacraments, you have fully understood everything that you were baptized in the name of the Trinity. In all that we have done, the mystery of the Trinity has been preserved. Everywhere, there is the Father and the Son and the Holy Spirit, one operation, one sanctification, although some things may seem special. How? God who anointed you, and sealed you, and placed the Holy Spirit in your heart. Therefore, you have received the Holy Spirit in your heart.”
Source
407
A.D.
John Chrysostom Patristic
A.D. 347–407
“After these words, after the renunciation of the devil and the covenant with Christ, inasmuch as you have henceforth become his very own and have nothing in common with that evil one, he straightway bids you to be marked and places on your forehead the sign of the cross. That savage beast is shameless, and when he hears those words, he grows more wild—as we might expect—and desires to assault you on sight. Hence God anoints your countenance and stamps thereon the sign of the cross. In this way God holds in check all the frenzy of the Evil One, for the devil will not dare to look on such a sight. Just as if he had beheld the rays of the sun and had leaped away, so will his eyes be blinded by the sight of your face and he will depart. For through the chrism the cross is stamped on you.… And that you may again know that it is not a man but God himself who anoints you by the hand of the priest, listen to St. Paul when he says: "It is God who makes both us and you stand firm in Christ, who has anointed us."”
Source
“"Now He which stablisheth us with you in Christ, and anointed us, is God; Who also sealed us, and gave us the earnest of the Spirit in our hearts." Again, from the past He stablisheth the future. For if it is He that establisheth us in Christ; (i.e., who suffereth us not to be shaken from the faith which is in Christ;) and He that anointed us and gave the Spirit in our hearts, how shall He not give us the future things? For if He gave the principles and the foundations, and the root and the fount, (to wit, the true knowledge of Him, the partaking of the Spirit,) how shall He not give the things that come of these: for if for the sake of these those are given, much more will he supply those. And if to such as were enemies he gave these, much more when now made friends will He "freely give" to them those. Wherefore He said not simply "the Spirit," but named "earnest," that from this thou mightest have a good hope of the whole as well. For did He not purpose to give the whole, He would never have chosen to give "the earnest" and to waste it without object or result. And observe Paul's candor. For why need I say, saith he, that the truth of the promises standeth not in us? The fact of your standing unwavering and fixed is not in us, but this too is of God; "for" saith he, "He who stablisheth us is God." It is not we who strengthen you: for even we also need Him that stablisheth. So then let none imagine that the Preaching is hazardous in us. He hath undertaken the whole, He cared for the whole. And what is, "anointed," and "sealed?" Gave the Spirit by Whom He did both these things, making at once prophets and priests and kings, for in old times these three sorts were anointed. But we have now not one of these dignities, but all three preeminently. For we are both to enjoy a kingdom and are made priests by offering our bodies for a sacrifice, (for, saith he, "present your members a living sacrifice unto God;) and withal we are constituted prophets too: for what things "eye hath not seen, nor ear heard," these have been revealed unto us.”
Source

Scholastic

c. 1100 – 1500
1272
A.D.
Thomas Aquinas Catholic
1225–1274
“The Apostle, having won the good will of the Corinthians, next adds his excuse, and concerning this he does three things. First he sets forth his intention; second, under the form of a question, he sets out the accusation made against him by them, at the words when therefore this, etc.; third, he excuses himself, at the words but God is faithful. Concerning the first, it should be known that the Apostle, in a first letter (which we do not have) sent by him to the Corinthians, or through a messenger, had promised them that he would come to them first, before going into Macedonia, and through them would go into Macedonia, and again from there would return to Achaia, in which Corinth is, and from Achaia into Judea; but afterward, in the second letter, which we have as the first, he writes to them that he would go first into Macedonia, and afterward come to Corinth. Since therefore, according to this, it seems contrary to the first promise, the Apostle now excuses himself concerning this, setting forth first the promise itself as it was first made, and therefore he says and in this confidence, as if to say: you know my purity and my sincerity, and you are my witnesses, and my glory; therefore in this confidence, that is, trusting in this — since we hope to be glorified through one another — I wished to come to you first, that you might have a second grace, because a second visitation and confirmation in the faith is called a second grace with respect to the conversion which they first had through his ministry and preaching. And through you to pass into Macedonia, and again from Macedonia to come to you, and by you to be led on into Judea. This is the order of the first promise, but in the preceding letter the order is contrary, as has been said. Next he sets forth, under the form of a question, the accusation of this change, by which the Corinthians accused him, saying when therefore I had willed this, etc. Two things they imputed to him from this: fickleness, because he had changed his purpose — Ecclesiasticus 27:12: the fool is changed as the moon — and carnality, because it seemed to them that he had done this from some carnal and human affection. Hence he touches on these two, and first fickleness, and so he says did I use fickleness, if I did not do what I once willed? Far from it. Esther 16:9: nor should you think, if we command different things, that it comes from fickleness of mind. Psalm 34:18: in a weighty people, etc. Second he touches on carnality when he says or do the things which I think — whether to be done or to be left undone — do I think according to the flesh, that is, according to some carnal affection, so that with me there is yes and no, that is, affirmation and negation? Below, 10:2: they think that we walk according to the flesh. James 1:8: a man double-minded, etc. Having set out their accusation, he next excuses himself, saying but God is faithful, etc., and concerning this he does two things. First he intimates that he had not lied; second he shows the manner in which he was not lying, at the words but he who confirms, etc. That he had not lied, he excuses himself in two ways, namely from custom, and from cause. From custom indeed, because it ought not to be believed that someone easily lies who has never been found a liar; and according to this exposition, but God is faithful, etc., is taken in the force of an oath, as if to say: let God be my witness, that my word — namely of preaching — which was among you, is not in it yes and no, that is, there is no falsity in it. Deuteronomy 32:4: God faithful, and without any, etc. But if but God is faithful, etc., be taken for the truth of the divine promise, then the sense is: God is faithful, that is, he keeps his promises. Now he had promised to send to you preachers of truth, Jeremiah 3:15: I will give you shepherds according to heart, etc., and therefore, since I have been sent by him, our word which was, etc., as above. From cause he excuses himself, when he says for the Son of God. And this in two ways, namely the motive cause and the efficient cause, at the words but he who confirms, etc. Now the motive cause for not lying is this, that whoever takes up some office is naturally moved toward the things that are fitting to that office, and not toward the contrary. But it is evident that the apostolic office is to preach the truth; therefore he is not moved toward the contrary of truth, which is to lie. And concerning this he does three things. First he proves the truth of his own word through the word of Christ; second, the truth of Christ through the word of God, at the words for how many soever, etc.; third he concludes his intention, at the words therefore also through him, etc. He says therefore first: I say that our words ought to be reckoned true, and they are true, because we have preached Christ, in whom there was no falsity. And this is what he says, for the Son of God, Christ, who has been preached by us among you; by me, namely principally, and Silvanus, secondarily (this is Silas, of whom mention is made in Acts 18:5), and Timothy, of whom mention was made above. For these two were with the Apostle when he first converted them. In him, namely the Son of God, there was not yes and no, that is, falsity, nor did he do what was not fitting. But in him there was yes, that is, truth; for the true and being are convertible. John 14:6: I am the way, the truth, and the life. But because what he says might seem doubtful — that in Christ there was no falsity — he immediately proves this, adding for how many soever, etc. And he proves it in this way. It is evident that in that which is manifestative of the divine truth there cannot be falsity; the Son of God came to manifest the divine truth by fulfilling through himself the promises made by God; therefore in him there is no falsity. And this is what he says: in the Son of God there is not yes and no, but yes, because how many soever promises of God — namely, as have been made to men — in him, that is in Christ, are, that is, are verified and fulfilled in Christ. Romans 15:8: I say that Jesus Christ was a minister, etc. To confirm, etc. From these things, therefore, he concludes that since his words are true — because he preaches the Son of God, in whom is truth — therefore also through him, namely Christ, we say, amen to God, that is, true. Apocalypse 3:14: these things says the Amen, the faithful witness, etc. Isaiah 65:16: he who is blessed on the earth shall be blessed in God, amen, etc. And this truth we say to God, that is, to the honor of God, namely manifesting his truth and our glory, because our glory is your conversion. Or our glory, because our glory is to show forth and preach the word of God. Next, when he says but he who confirms, etc., the Apostle proves that he has not lied, through the efficient cause. For although a man, by free will, can use his tongue to speak either truth or falsehood, nevertheless God can confirm a man so firmly in truth that he speaks nothing but true things. If therefore God were to confirm someone in truth, it is manifest that he would not speak falsehood; but God confirms us in truth; therefore, etc. And therefore he says that it is God who confirms you with us in Christ, that is, in the true preaching of Christ, as if to say: if Christ were outside us, we could lie, but since he is with us, and we are in Christ, we do not lie. Psalm 74:4: I have confirmed its pillars, etc. We are therefore in Christ in two ways, namely through grace and through glory. Through grace indeed we are in him insofar as we have been anointed with the grace of the Holy Spirit, and have been made members of Christ, and joined to him. By which grace also Christ was anointed according as he is man. Psalm 44:8: God has anointed you, etc. And from the fullness of this anointing it overflowed onto all who are his, like the ointment on the head — namely on Christ — which descended, etc. And therefore he says that God has anointed us. He has anointed us, I say, as kings and priests. Apocalypse 5:10: you have made us to God, etc. 1 Peter 2:9: but you are a chosen race, etc. But the union which is through glory we do not have in reality, but in a certain hope, insofar as we have a firm hope of eternal life. And we have a twofold certitude of hope of attaining this union. One is through a sign, the other through a pledge. Through an evident sign, because of the faith. Hence he says he has sealed us with the sign of the faith of Christ. Likewise the sign of the cross. Ezekiel 9:4: mark thau, that is, the sign of the cross. Apocalypse 7:3: till we sign the servants of our God, etc. And this through the Holy Spirit. Romans 8:9: if anyone does not have the Spirit of Christ, etc. And therefore it is a special and certain sign of attaining eternal life to be configured to Christ. Canticle of Canticles 8:6: set me as a seal, etc. Or he has sealed us with the sign of life. But through the pledge, the greatest, because of the Holy Spirit, and therefore he says he has given the pledge of the Spirit in our hearts. Of which it is certain that no one can take it from us. But note, in a pledge two things are to be considered, namely that it produces the hope of having the thing, and that it is worth as much as the thing is worth, or more; and these two things are found in the Holy Spirit. For if we consider the substance of the Holy Spirit, thus the Holy Spirit is worth as much as eternal life, which is God himself, because he is worth as much as all three persons. But if the manner of having be considered, thus it produces hope, and not possession, of eternal life, because we do not yet perfectly have it in this life. And therefore we are not perfectly blessed, except when we shall have it perfectly in our homeland. Ephesians 1:13: you have been sealed with the Spirit. Next, when he says but I call God to witness, etc., he excuses himself concerning the fact that he did not come: and this through an oath, which is a greater thing. And concerning this he does three things. First he sets forth his excuse; second he answers a tacit question, at the words not that we dominate; third he explains what he says, at the words for by faith you stand. Now he excuses himself through a twofold oath. One of attestation, when he says but I call God to witness, the other of execration, when he says upon my soul, that is, against my soul. Romans 1:9: God is my witness, etc. As witness, I say, I call upon God, because I did not come again, that is, after the first time, or after I departed from you; and this I did, sparing you, namely because he knew them to be incorrigible. Hence, if he had gone then, either he would have punished them, and thus perhaps they would have withdrawn entirely from the faith; or he would not have punished them, and thus he would have given them occasion to sin the more. But because someone might say: why do you say sparing you? Are you not our lord? He therefore next removes this, saying not, I say, that we dominate over your faith, but are helpers, etc., as if to say: I do not say this as a lord, but as a fellow-helper. 1 Peter 5:3: not as lording it over the clergy, etc. A helper, I say, of your joy, or of your amendment. But why he says, of your faith, he next explains, saying for by faith you stand, that is, you stand in this grace of Christ through faith.”

Post-Reformation

c. 1650 – 1900
1771
A.D.
John Gill Reformed
1697–1771
“Now he which stablisheth us with you,.... Two things are in this verse ascribed to God. First, the establishing of the saints in Christ; in which may be observed, that the people of God are in a firm, settled, established state and condition; they are encircled in the arms of everlasting love; they are secure of the favour of God; they are engraven on his hands, and set as a seal on his heart, from whence they can never be removed; they are taken into his family by adopting grace; and will never be turned out; they are in a state of justification, and shall never enter into condemnation; they are regenerated and sanctified by the Spirit of God, and shall never finally and totally fall from that grace they have received. This their establishment is "in" Christ, and in no other. They had no stability in Adam, nor have they any in themselves; their standing is alone in him; the unchangeable love and favour of God, which is their grand security, is in Christ; the covenant of grace, in which is all their salvation, is made and stands fast with him; their persons, with all their grace and glory, are put into his hands, and made his care and charge, and there they are safe. They are espoused unto him, made one with him, incorporated into him, and are built upon him the rock of ages, where they are so established, that hell and earth cannot shake them, so as to remove and unsettle them from this foundation: one and all of them, and all together, are established in him, us with you; all the elect of God are alike, and together in Christ, and have the same place and standing in his love, power, and care; they make up one body, of which Christ is the head, and not one of them shall be lost, whether they be Jews or Gentiles, ministers or private believers; for so this phrase may be interpreted, "us" Jews "with you" Gentiles, or "us" ministers "with you" believers. This work of establishing the saints in Christ is wholly the Lord's act; he is God that does it; which does not contradict the word and ordinances being means of establishment; nor does it hinder or discourage persons making use of means for their stability; for the apostle here is not speaking so much of the stability of hearts, frames, and exercise of grace, as of state; though a firm, steady, and stable assurance of interest in Christ, is what God gives by his Spirit. The apostle's view seems to be this, that whatever steadfastness and stability the saints have, whether ministers or people, they ought to ascribe it entirely to God, Father, Son, and Spirit. "Secondly", the anointing of them: he hath anointed us; which is to be understood either of the unction of ministers, with the gifts of the Spirit for ministerial service; or rather of the anointing of private Christians with the grace of the Spirit, compared to oil or ointment, in allusion to the anointing oil under the law, by which the tabernacle, and its vessels, Aaron, and his sons, were anointed, who were typical of the saints and priests of God under the Gospel; or to the lamp oil in the candlestick, which was pure, and for light; or to oil in common, for its sweet smell, refreshing nature, and for its usefulness for ornament and healing. This also is the Lord's work, and not man's; this unction comes from the God of all grace, through Christ, by the Spirit.”
Source
1832
A.D.
Adam Clarke Methodist
1762–1832
“Now he which stablisheth us with you - It is God that has brought both us and you to this sure state of salvation through Christ; and he has anointed us, giving us the extraordinary influences of the Holy Ghost, that we might be able effectually to administer this Gospel to your salvation. Through this unction we know and preach the truth, and are preserved by it from dissimulation and falsity of every kind.”
Source
1849
A.D.
1774–1849
“This must needs be true, because he is God, who hath confirmed us with you, both us and you in Christ, in the faith, and grace of Christ crucified, who hath anointed us with divine graces, who hath sealed us, as it were, by an indelible character, in the sacraments of baptism, and confirmation, and ordination, when we were made ministers of Christ, who in this manner hath given the pledge [5] of his holy Spirit in our hearts, a sufficient pledge and earnest of his graces in this life, and of the glory he has prepared for us in the next. (Witham) — By these texts, and Ephesians iv., the Catholic Church teaches, that we are anointed and consecrated to the service of God, and sealed with a spiritual and distinctive mark, called by divines, a character, (see St. Jerome in Ephesians iv.; St. Cyril, cateches. 17.) which, as it is indelible, can never be iterated. The same is true of confirmation, and holy orders. See St. Augustine, cont. Parm. chap. xiii. & Conc. Tarrac. chap. vi.”
Source
1871
A.D.
1871
“stablisheth us . . . in Christ--that is, in the faith of Christ--in believing in Christ. anointed us--As "Christ" is the "Anointed" (which His name means), so "He hath anointed (Greek, "chrisas") us," ministers and believing people alike, with the Spirit (Co2 1:22; Jo1 2:20, Jo1 2:27). Hence we become "a sweet savor of Christ" (Co2 2:15).”
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.