Here is the text:

“Therefore, I bow my knees before the Father of our Lord Jesus Christ, after whom every family in the heavens and on earth is named, that He may grant you—in accordance with the riches of His glory—to become staunch in power through His Spirit in the inner man, so that Christ may dwell fully in your hearts through faith, and that you, rooted and grounded in love, may be strengthened to grasp, together with all the saints, what is the breadth and length and depth and height (and to know the love of Christ, which surpasses all knowledge), so that you may be completed unto the whole completion of God. Now to Him who can do far more, beyond all that we ask or conceive—according to the power that works in us—to Him be the glory in the called-out community and in Christ Jesus, for all the generations of the eon of the eons! Amen!”
Eph 3:14-21

The prayer begins with the word “Therefore.” This connects it to what has gone before. In today’s language one might also say “So then!” Paul is picking up the thread of his previous remarks. The prayer has something to do with what precedes it.

Therefore, he bows his knees—a way of giving the prayer a religious form. Bowing the knees is figurative language, a familiar way of praying. He says, “Therefore, I bow my knees before the Father of our Lord Jesus Christ.” With these words Paul describes that he is now speaking a prayer. In it he addresses the Father of our Lord Jesus Christ—that is, God. In the letter to the Corinthians he wrote: “Yet for us there is one God, the Father, out of whom is the all (and we are turned toward Him), and one Lord, Jesus Christ, through whom the all has come to be (and we are through Him)” (1 Cor 8:6). For Paul it is clear: God is the Father, namely “the Father of our Lord Jesus Christ.” Already in Ephesians 1:3 he spoke of the “God and Father of our Lord Jesus Christ.”

He describes the Father with further words: “after whom every family in the heavens and on earth is named.” This indicates that the Father stands above all. That is why the Father is God. Paul adds, “that He may grant you—in accordance with the riches of His glory—to become staunch in power through His Spirit in the inner man, so that Christ may dwell fully in your hearts through faith.” The distinction from Christ is clear. Here Paul prays that the Father, through His Spirit, would strengthen the recipients of the letter in the inner man, so that Christ, through this and through faith, may dwell fully in their hearts.

• Who was to do the strengthening? God’s Spirit.
• Where was this spirit strengthening the believers? In the inner man.
• To what end were people to be strengthened? So that Christ, through faith, might dwell fully in their hearts.

This follows on from what came before and thus has everything to do with what Paul has been recounting so far. It concerned a mystery, namely the mystery of Christ, which had previously been unknown (Eph 3:4-5). The mystery concerned the new equality of Jews and Gentiles. Never before had this been defined so clearly. It was a mystery that Paul reveals in the letter to the Ephesians. He wrote: “To me, the very least of all the saints, was this grace given, to bring to the Gentiles the untraceable riches of Christ as gospel, and to enlighten everyone as to the administration of the mystery which, from the eons, had been hidden in God” (Eph 3:8-9).

Against this background Paul becomes thankful. That is why he bows his knees in prayer. When he further mentions that this Father is the one “after whom every family in the heavens and on earth is named” (Eph 3:15), he is emphasizing that this Father is God for all equally. Distinctions between Jews and Gentiles that still mattered until then no longer do so.

In this prayer Paul formulates a concern. For him it is logical. For his audience it was entirely new. Perhaps that is why Paul sums up these thoughts as a prayer, so that they take on meaning as a spiritual reality. This was not about a pragmatic innovation, the kind where one adapts the message slightly so the hearers can understand it. Rather, it was about a sweeping new orientation, unknown until then. The message was brand new and unheard of.

Paul now wishes that God, who stands above all, the Father of our Lord Jesus Christ, would strengthen the hearers so that Christ, through faith, may dwell in their hearts. This is both a wish and a realization of faith. The strengthening is not necessary for theological highlights; rather, Christ himself is to dwell in their hearts. Not in the mind, but in the heart. The chosen words carry meaning.

The goal is this:

“…and that you, rooted and grounded in love, may be strengthened to grasp, together with all the saints, what is the breadth and length and depth and height (and to know the love of Christ, which surpasses all knowledge), so that you may be completed unto the whole completion of God.”
Eph 3:17-19

The word “love” is mentioned twice here. First, the point is that Christ dwells in their hearts, and that they are therefore (!) rooted and grounded in love. This is meant to build up. Yet this still was not the goal. The goal is only now mentioned: “to grasp, together with all the saints.” The emphasis now falls on “all the saints,” which includes both Jews and Gentiles. That was precisely what had just been proclaimed. Now they stand in a new place. They are no longer subordinate to the people of Israel. They are no longer “guests of the covenants of promise” (Eph 2:12), but full members of the family of God (Eph 2:19). In this new situation Paul prays that they should grasp something together with all the saints. As equals.
Being rooted and grounded in love is one thing. But they are also to know the love of Christ, which surpasses all knowledge. Yet this is not a personal feeling but a communal experience. Together “with all the saints,” they are to grasp the breadth, length, depth, and height—so to speak, the full scope of this message, of this God and Christ. That scope is not to be found in Bible knowledge, but the love of Christ surpasses all knowledge.

Here we can clearly see Paul’s aim: faith leads to love. The gospel of the grace of God and the mystery of Christ bring Gentiles and Jews together in the community. This is comprehensive. Together we should learn to understand this. The same holds for the shared recognition of the love of Christ, which surpasses all knowledge.

All these things are meant to lead somewhere. Paul describes it as follows:

“So that you may be completed unto the whole completion of God.”
Eph 3:19

A completion is the final fulfillment. We are to be finally fulfilled unto the final fulfillment of God. That is a genuine win-win situation. We gain, and God gains. That is how the apostle sketches it.

This is not about special effects or particular benefits for this life, such as health, prosperity, or the like. When Paul prays, that is not the issue. He is concerned with something else. He speaks of what Christ means today for all the Gentile nations of this world. That was the mystery of Christ, about which he reported at length. His concern is that people come to know God. That fulfills not only us, but also corresponds to God’s own goal (1 Cor 15:28).
In these reflections one should also think of what Paul had already written earlier:

“In Him you too are being built together into a dwelling place of God in spirit.”
Eph 2:22

The final two verses of this prayer seem to be a renewed acknowledgment of God, serving on the one hand as testimony and summary, and on the other as recognition. It is written in the form of a doxology:

“Now to Him who can do far more, beyond all that we ask or conceive—according to the power that works in us—to Him be the glory in the called-out community and in Christ Jesus, for all the generations of the eon of the eons! Amen!”
Eph 3:20-21

The reference is to God, the Father. To Him be the glory (this is the doxology) in the called-out community and in Christ Jesus. In Paul we find no cult of Jesus, but a worship of God. God’s glorification takes place in two locations: in the called-out community and in Christ Jesus. The apostle mentions both. This is also meant to make clear that faith, praise, and the glorification of God are lived out in the community. In other words, it is not irrelevant how we conduct ourselves, and what we do and leave undone.

God’s glorification also applies to Christ Jesus. In Him, God is glorified. We have no influence over this, but it is the insight that comes from Paul’s faith and understanding. It is like a reminder of the foundations and the goal of the gospel. At the beginning of this letter Paul already identified himself as “apostle of Christ Jesus.” This was “through the will of God” (Eph 1:1).

If we consider the disclosure of previously unknown mysteries, and the equal standing of Jews and Gentiles, then we get a sense of how God works. He is more generous, more gracious, and wiser beyond measure than one could expect. “The apparent foolishness of God,” Paul wrote to the Corinthians, “is wiser than men, and the apparent weakness of God is stronger than men” (1Cor 1:25). This is the God who “can do far more, beyond all that we ask or conceive.”

What we can learn from this is that Paul is not simply proclaiming doctrine, theology, or wisdom; he himself is full of wonder at the greatness of God, which surpasses everything he can imagine. This wonder is not knowledge but, like the love of Christ mentioned earlier, surpasses all knowledge. It is more than we can conceive.