The interpretation timeline
1 Peter 2:9 Douay-Rheims

But you are a chosen generation, a kingly priesthood, a holy nation, a purchased people: that you may declare his virtues, who hath called you out of darkness into his marvellous light:

A.D. 108 – 1871 15 witnesses

Patristic

before A.D. 750
108
A.D.
c. A.D. 50–107
“Now the way is unerring, namely, Jesus Christ. For, says He, "I am the way and the life." And this way leads to the Father. For "no man," says He, "cometh to the Father but by Me." Blessed, then, are ye who are God-bearers, spirit-bearers, temple-bearers, bearers of holiness, adorned in all respects with the commandments of Jesus Christ, being "a royal priesthood, a holy nation, a peculiar people," on whose account I rejoice exceedingly, and have had the privilege, by this Epistle, of conversing with "the saints which are at Ephesus, the faithful in Christ Jesus." I rejoice, therefore, over you, that ye do not give heed to vanity, and love nothing according to the flesh, but according to God.”
Source
165
A.D.
Justin Martyr Patristic
A.D. 100–165
“And we are just as if drawn out from the fire, when purified from our former sins, and [rescued] from the affliction and the fiery trial by which the devil and all his coadjutors try us; out of which Jesus the Son of God has promised again to deliver us, and invest us with prepared garments, if we do His commandments; and has undertaken to provide an eternal kingdom [for us]. For just as that Jesus (Joshua), called by the prophet a priest, evidently had on filthy garments because he is said to have taken a harlot for a wife, and is called a brand plucked out of the fire, because he had received remission of sins when the devil that resisted him was rebuked; even so we, who through the name of Jesus have believed as one man in God the Maker of all, have been stripped, through the name of His first-begotten Son, of the filthy garments, i.e., of our sins; and being vehemently inflamed by the word of His calling, we are the true high priestly race of God, as even God Himself bears witness, saying that in every place among the Gentiles sacrifices are presented to Him well-pleasing and pure. Now God receives sacrifices from no one, except through His priests.”
Source
215
A.D.
c. A.D. 150–215
“"But you are a chosen generation, a royal priesthood." [1 Peter 2:9] That we are a chosen race by the election of God is abundantly clear. He says royal, because we are called to sovereignty and belong to Christ; and priesthood on account of the oblation which is made by prayers and instructions, by which are gained the souls which are offered to God.”
Source
303
A.D.
c. A.D. 250–303
“"And He made us a kingdom and priests unto God and His Father." That is to say, a Church of all believers; as also the Apostle Peter says: "A holy nation, a royal priesthood."”
311
A.D.
c. A.D. 260–311
“Hail, thou people of the Lord, thou chosen generation, thou royal priesthood, thou holy nation, thou peculiar people-show forth His praises who hath called you out of darkness into His marvellous light; and for His mercies glorify Him.”
date
unknown
c. A.D. 380
“Hear this, you of the laity also, the elect Church of God. For the people were formerly called "the people of God," [Exodus 19:5-6] and "an holy nation." [Hebrews 12:23] You, therefore, are the holy and sacred "Church of God, enrolled in heaven, a royal priesthood, an holy nation, a peculiar people," [1 Peter 2:9] a bride adorned for the Lord God, a great Church, a faithful Church.”
Source
date
unknown
c. A.D. 400
“For in this "do ye appear to the world as lights, in that ye give heed to the Word of life," [Philippians 2:15-16] and thus ye are in truth the praise, and the boast, and the crown of rejoicing, and the delight of good servants in our Lord Jesus Christ. For all who see you will "acknowledge that ye are the seed which the Lord hath blessed;" [Isaiah 61:9] in very deed a seed honourable and holy, and "a priestly kingdom, a holy people, the people of the inheritance," [1 Peter 2:9] the heirs of the promises of God; of things which do not decay, nor wither; of "that which eye hath not seen, and ear hath not heard, and which hath not come up into the heart of man; of that which God hath prepared for those who love Him and keep His commandments." [1 Corinthians 2:9]”
Source
430
A.D.
Augustine of Hippo Patristic
A.D. 354–430
“In ancient times only one high priest was anointed, but now all Christians are anointed.”
461
A.D.
Leo the Great Patristic
c. A.D. 400–461
“All who have been born again in Christ are made kings by the sign of the cross and consecrated priests by the anointing of the Holy Spirit.”

Post-Reformation

c. 1650 – 1900
1771
A.D.
John Gill Reformed
1697–1771
“Which in time were not a people,.... A "Loammi" being put upon them; see Hos 1:9 to which the apostle here refers: God's elect, whether among Jews or Gentiles, were, from eternity, his chosen people, and his covenant people; and, as such, were given to Christ, and they became his people, and his care and charge; and he saved them by his obedience, sufferings, and death, and redeemed them to himself, a peculiar people: but then, before conversion, they are not a people formed by God for himself, and his praise; nor Christ's willing people, either to be saved by him, or to serve him; nor are they, nor can they be truly known by themselves, or others, to be the people of God: the Syriac version gives the true sense of the phrase, by rendering it "these who before were not" "reckoned or accounted a people"; that is, by others: but are now the people of God; being regenerated, called, and sanctified, they are avouched by God to be his people; they have the witness of the Spirit to their spirits, that they are the people of God; they can then claim their relation to God, and are known, acknowledged, and called the people of God, by others: which had not obtained mercy, but now have obtained mercy; being called formerly, Loruhamah, Hos 1:6 which passages the apostle has in view: before conversion there is mercy in God's heart towards his elect, and so there is in the covenant of grace, and which was shown in the provision of his Son, as a Saviour, in the mission of him, and redemption by him; but this is not manifested to them, until they are begotten again, according to abundant mercy, and then they obtain mercy; having in their regeneration an evident display of the mercy of God towards them, and an application of his pardoning grace and mercy, through the blood of his Son, unto them.”
Source
1832
A.D.
Adam Clarke Methodist
1762–1832
“Ye are a chosen generation - The titles formerly given to the whole Jewish Church, i.e. to all the Israelites without exception, all who were in the covenant of God by circumcision, whether they were holy persons or not, are here given to Christians in general in the same way; i.e. to all who believed in Christ, whether Jews or Gentiles, and who received baptism in the name of the Father, and of the Son, and of the Holy Ghost. The Israelites were a chosen or elected race, to be a special people unto the Lord their God, above all people that were upon the face of the earth, Deu 7:6. They were also a royal priesthood, or what Moses calls a kingdom of priests, Exo 19:6. For all were called to sacrifice to God; and he is represented to be the King of that people, and Father of those of whom he was king; therefore they were all royal. They were a holy nation, Exo 19:6; for they were separated from all the people of the earth, that they might worship the one only true God, and abstain from the abominations that were in the heathen world. They were also a peculiar people, λαος εις περιποιησιν, a purchased people; סגלה segullah, a private property, belonging to God Almighty, Deu 7:6; none other having any right in them, and they being under obligation to God alone. All these things the apostle applies to the Christians, to whom indeed they belong, in their spirit and essence, in such a way as they could not belong to the Hebrews of old. But they were called to this state of salvation out of darkness - idolatry, superstition, and ungodliness, into his marvellous light - the Gospel dispensation, which, in reference to the discoveries it had made of God, his nature, will, and gracious promises towards mankind, differed as much from the preceding dispensation of the Jews, as the light of the meridian sun from the faint twinkling of a star. And they had these privileges that they might show forth the praises of Him who had thus called them; αρετας, the virtues, those perfections of the wisdom, justice, truth, and goodness of God, that shone most illustriously in the Christian dispensation. These they were to exhibit in a holy and useful life, being transformed into the image of God, and walking as Christ himself walked.”
Source
1849
A.D.
1774–1849
“You are... a purchased people, whom Christ purchased, bought and redeemed with the price of his precious blood. — That you may declare his [4] virtues; i.e. the excellencies and perfections of God, who hath called you, and now made you his people, which you were not, at least in this matter before, neither you that were Jews, nor especially you that were Gentiles. Wi.”
Source
1863
A.D.
1871
A.D.
1871
“Contrast in the privileges and destinies of believers. Compare the similar contrast with the preceding context. chosen--"elect" of God, even as Christ your Lord is. generation--implying the unity of spiritual origin and kindred of believers as a class distinct from the world. royal--kingly. Believers, like Christ, the antitypical Melchisedec, are at once kings and priests. Israel, in a spiritual sense, was designed to be the same among the nations of the earth. The full realization on earth of this, both to the literal and the spiritual Israel, is as yet future. holy nation--antitypical to Israel. peculiar people--literally, "a people for an acquisition," that is, whom God chose to be peculiarly His: Act 20:28, "purchased," literally, "acquired." God's "peculiar treasure" above others. show forth--publish abroad. Not their own praises but His. They have no reason to magnify themselves above others for once they had been in the same darkness, and only through God's grace had been brought to the light which they must henceforth show forth to others. praises--Greek, "virtues," "excellencies": His glory, mercy (Pe1 2:10), goodness (Greek, Pe1 2:3; Num 14:17-18; Isa 63:7). The same term is applied to believers, Pe2 1:5. of him who hath called you-- (Pe2 1:3). out of darkness--of heathen and even Jewish ignorance, sin, and misery, and so out of the dominion of the prince of darkness. marvellous--Peter still has in mind Psa 118:23. light--It is called "His," that is, God's. Only the (spiritual) light is created by God, not darkness. In Isa 45:7, it is physical darkness and evil, not moral, that God is said to create, the punishment of sin, not sin itself. Peter, with characteristic boldness, brands as darkness what all the world calls light; reason, without the Holy Spirit, in spite of its vaunted power, is spiritual darkness. "It cannot apprehend what faith is: there it is stark blind; it gropes as one that is without eyesight, stumbling from one thing to another, and knows not what it does" [LUTHER].”
Source

Undated

date unknown
date
unknown
Glossa Ordinaria Medieval
“But you are a chosen generation. This testimony of praise, once given to the ancient people through Moses, the Apostle gives to the Gentiles who believe in Christ, who, as a corner stone, united the Gentiles into that salvation which Israel had had in itself. A royal priesthood. United to the body of the high priest, they were bound to hope for a kingdom and to offer to God the victims of an unspotted manner of life. Of acquisition, in the blood of his redemption, as the people of Israel was once redeemed out of Egypt by the blood of the lamb. Whence also in the following verse he mystically calls to mind the ancient history, and teaches that it was fulfilled specially in one people. That you may declare. As they, freed from Egypt, sang a song of triumph to the Lord, so we, after the darkness has been dissolved, after remission received through Christ, who leads us to the fatherland of the heavenly brightness, ought to repay to God thanks worthy of the heavenly benefits.”
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.