9 And to make all men see what is the fellowship of the mystery, which from the beginning of the world hath been hid in God, who created all things by Jesus Christ:
[AD 407] John Chrysostom on Ephesians 3:8-11
"Unto me, who am less than the least of all saints, was this grace given, to preach unto the Gentiles the unsearchable riches of Christ; and to make all men see what is the dispensation of the mystery, which from all ages has been hid in God, who created all things: to the intent that now unto the principalities and the powers in the heavenly places might be made known through the Church the manifold wisdom of God, according to the eternal purpose, which He purposed in Christ Jesus our Lord."

They who go to the physician's have not merely to go there and nothing further; they have to learn how to treat themselves, and to apply remedies. And so with us then who come here, we must not do this and nothing else, we must learn our lesson, the surpassing lowliness of Paul. What? When he was about to speak of the vastness of the grace of God, hear what he says, "Unto me, who am less than the least of all saints, was this grace given." Lowliness indeed it was even to bewail his former sins, although blotted out, and to make mention of them, and to hold himself within his true measure as where he calls himself "a blasphemer, and a persecutor, and injurious;" [1 Timothy 1:13] yet nothing was equal to this: for "formerly," says he, such was I; and again he calls himself, "one born out of due time." [1 Corinthians 15:8] But that after so many great and good deeds and at that time he should thus humble himself, and call himself "less than the least of all," this is indeed great and surpassing moderation. "To one who am less than the least of all saints;" he says not, "than the Apostles." So that that expression is less strong than this before us. There his words are, "I am not meet to be called an Apostle." [1 Corinthians 15:9] Here he says that he is even "less than the least of all saints;" "to me," says he, "who am less than the least of all saints was this grace given." What grace? "To preach unto the Gentiles the unsearchable riches of Christ, and to make all men see what is the dispensation of the mystery, which from all ages has been hid in God, who created all things, to the intent that now unto the principalities and the powers in the heavenly places, might be made known through the Church the manifold wisdom of God." True, to man it was not revealed; and are you enlightening Angels and Archangels and Principalities and Powers? I am, says he. For it was "hid in God," even "in God who created all things." And do you venture to utter this? I do, says he. But whence has this been made manifest to the Angels? By the Church. Again he says, not merely the manifold (ποικίλος) but the much-manifold (πολυποίκιλος) wisdom, that is, "the multiplied and varied." What then is this? Did not Angels know it? No, nothing of it; for if Principalities knew it not, much less could Angels ever have known it. What then? Did not even Archangels know it? No, nor even they. But whence were they going to know it? Who was to reveal it? When we were taught it, then were they also by us. For hear what the Angel says to Joseph; "You shall call His Name Jesus, for it is He that shall save His people from their sins." [Matthew 1:21]

Paul himself was sent to the Gentiles, the other Apostles to the Circumcision. So that the more marvellous and astonishing commission was given, says he, "to me, who am less than the least." And this too was of grace, that he that was least should have the greatest things entrusted to him; that he should be made the herald of these tidings. For he that is made a herald of the greater tidings, is in this way great.

"To preach unto the Gentiles the unsearchable riches of Christ."

If His "riches are unsearchable," and that too after his appearing, much more is His essence. If it is still a mystery, much more was it before it was made known; for a mystery he calls it on this account, because neither did the Angels know it, nor was it manifest to any one else.

"And to make all men see," says he, "what is the dispensation of the mystery which from all ages has been hid in God, who created all things."

Angels knew only this, that "The Lord's portion was His people." [Deuteronomy 32:8-9] And again it is said, "The Prince of Persia withstood me." [Daniel 10:13] So that it is nothing to be wondered at that they were ignorant of this; for if they were ignorant of the circumstances of the return from the Captivity, much more would they be of these things. For this is the gospel. "It is He that shall save," it says, "His people." [Matthew 1:21] Not a word about the Gentiles. But what concerns the Gentiles the Spirit reveals. That they were called indeed, the Angels knew, but that it was to the same privileges as Israel, yea, even to sit upon the throne of God, this, who would ever have expected? Who would ever have believed?

"Which has been hid," says he, "in God."

This "dispensation," however, he more clearly unfolds in the Epistle to the Romans. "In God," he continues, "who created all things by Jesus Christ." And he does well to say "by Jesus Christ;" forasmuch as He who created all things by Him, reveals also this by Him; for He has made nothing without Him; for "without Him," it is said, "was not anything made." [John 1:30]

In speaking of "principalities" and "powers," he speaks both of those above and those beneath.

"According to the eternal purpose." It has been now, he means, brought to pass, but not now decreed, it had been planned beforehand from the very first. "According to the eternal purpose which He purposed in Christ Jesus our Lord." That is, according to the eternal foreknowledge; foreknowing the things to come, i.e., he means the ages to come; for He knew what was to be, and thus decreed it. According to the purpose of the ages, of those, perhaps, which He has made by Christ Jesus, because it was by Christ that every thing was made.

[AD 160] Shepherd of Hermas on Ephesians 3:9
God, who dwells in the heavens, and made out of nothing the things that exist, and multiplied and increased them on account of His holy Church,

[AD 370] Gaius Marius Victorinus on Ephesians 3:9
When he speaks of making “all men see the plan,” this includes both Israel and the Gentiles. Paul had doubtless received the gospel for the Gentiles. But the Jews too can see the plan if they follow and obey.

[AD 370] Gaius Marius Victorinus on Ephesians 3:9
Christ is the only begotten Son of God, and through him all the rest are created. Through him the works of God are created, as God works in and through him. All ages of time are subsequent to Christ, being made by Christ.… Therefore, even though God is acknowledged as the Creator, God is nonetheless Creator through Christ. The term Creator therefore does not pertain simply to God as such but pertains to Christ and through Christ to God. Christ who was eternally begotten created all things in time. God worked and created all things through Christ.

[AD 420] Jerome on Ephesians 3:9
These riches of his generosity were “hidden from all past ages in God,” the Creator of all. Where are Marcion, Valentinus and the other heretics who say that there is one creator of the visible world and another creator of the invisible?… However, the phrase “mystery hidden from the ages” could also be understood to mean that the very ages of time remained ignorant of his generosity when all spiritual and rational creatures who inhabited all previous ages remained unenlightened.