For this reason I bow my knees before the Father, from whom every family in heaven and on earth is named, that according to the riches of his glory he may grant you to be strengthened with power through his Spirit in your inner being, so that Christ may dwell in your hearts through faith - that you, being rooted and grounded in love, may have strength to comprehend with all the saints what is the breadth and length and height and depth, and to know the love of Christ that surpasses knowledge, that you may be filled with all the fullness of God. Now to him who is able to do far more abundantly than all that we ask or think, according to the power at work within us, to him be glory in the church and in Christ Jesus throughout all generations, forever and ever. Amen. (Ephesians 3:14-21)
Part way through his letter, Paul stops to say a prayer for his readers, that they would be strengthened by God and granted fullness in Christ. He begins with "For this reason...", turning us back to the preceding verses in which he says, "Of this gospel I was made a minister according to the gift of God's grace... to preach to the Gentiles the unsearchable riches of Christ, and to bring to light for everyone what is the plan of the mystery hidden for ages in God who created all things... This was according to the eternal purpose that he has realized in Christ Jesus our Lord, in whom we have boldness and access with confidence through our faith in him." (vv. 7-9, 11-12) He is praying for the Ephesians because this is his role, ordained by God, and given to Paul "according to the gift of God's grace, which was given me by the working of his power." (v. 7) This a fitting way for Paul to describe his call to ministry, which came about in an experience unlike any of us have ever had (see Acts 9) - through a blinding vision of the risen Jesus on the road to Damascus. And when the disciple Ananias was told to go to Paul and heal his blindness and he objected, "the Lord said to him, 'Go, for he is a chosen instrument of mine to carry my name before the Gentiles and kings and the children of Israel. For I will show him how much he must suffer for my name.'" (Acts 9:15-16)
So Paul was a divinely designated person, called out to fulfill part of God's special purpose for the Church of Jesus Christ. This sounds astonishing, and one may wonder at the notion of being such a person, set apart specifically by God to play a special role. The truth is, according to Paul's theology, that is exactly what every believer in Christ is! Paul makes this clear in the opening of this letter to the Ephesians when he says that God "has blessed us in Christ with every spiritual blessing in the heavenly places, even as he chose us in him before the foundation of the world, that we should be holy and blameless before him." (Eph. 1:3-4) Every believer, not simply the apostles or prophets or overseers of the early church, has been specifically chosen and set apart by God from eternity. So when Paul is praying for the Gentile churches as one specifically set apart by God to do so, he also recognizes that his audience (which includes us) is part of the same body along with himself, established by God and built on the same foundation in Christ.
That is something of an aside, but it is important to note how Paul is fulfilling his role as a minister to the Gentiles here by praying for the Ephesians, and how the nature of that calling is the same as our own, even if the specific roles we fulfill differ. So Paul, as the apostle to the Gentiles, prays for the Ephesians, "that according to the riches of his [God's] glory he may grant you to be strengthened with power through his Spirit in your inner being," (Eph. 3:15) "so that" four things may happen, and happen consecutively: first, "so that Christ may dwell in your hearts through faith." (v.17) This is the fundamental role that the Spirit plays in the lives of believers, and so it is fitting that Paul mentions this first - it is through the ministry of the Holy Spirit that sinful humans possess faith in Christ. It is by the power of the Spirit that Christ dwells in our hearts through faith, and this is central to everything else a Christian may do in his or her walk with Christ.
This faith that the Holy Spirit kindles in the hearts of believers doesn't simply grant us belief and serve no other purpose however. Paul asks that the Spirit would dwell in our hearts by faith, "that you, being rooted and grounded in love, may have strength to comprehend with all the saints what is the breadth and length and height and depth, and to know the love of Christ that surpasses knowledge, that you may be filled with all the fullness of God." (vv.17-19) So, Paul asks that the Holy Spirit will dwell in our hearts by faith in order that 1) Christians would comprehend the "breadth and length and height and depth" (more on this in a moment), 2) know Christ's love, 3) and be filled with all God's fullness.
When we read this, we ought to apply this to ourselves just as surely as we would apply Paul's prayer to his original audience. The hope of Christians is that the renewing power of God's Holy Spirit (through which Christ dwells in our hearts) would give us (for one) understanding. When Paul talks about the breadth, length, height, and depth, he is referring to the full measure of God's revealed being and the vastness of his plan for the ages (of which we're a part). Christians are supposed to be knowledgeable people, who have a passion for God that is grounded in their understanding of who God is. And without that understanding, our emotions about God - whatever they may be - will contain very little truth in them or reason behind them, because their source will not be in God as he truly is, but in ourselves as we prefer him to be. They will be less reflections of God and more reflections of ourselves.
Finally, Paul wants us to know Christ's love for us, so that we may be filled with all the fullness of God. (v.19) When I say that our emotions about God should be grounded in our true knowledge of God, that may sound a little frigid and, frankly, emotionless. But the most important part of the knowledge we are supposed to have about God, and about God in Christ, is his love for us. What we know about God fluidly translates into what we feel toward God, and it cannot work the other way around.
Now, as Paul makes very clear, there is something of a mystery to all of this, which is the source of his very curious hope for the Ephesians (and for us), that they would "know the love of Christ that surpasses knowledge." (v.19) 'What?' we might ask. It's a very striking statement, and a comment in the ESV study bible on this verse puts it very simply and beautifully: "To know what surpasses knowledge is the sublime privilege of the Christian." We often speak of God as ultimately incomprehensible, a being who can never fully be known by us in his infinitude. But nevertheless it is possible to know him (though never entirely), and we are to order our lives around that knowledge (though limited) of something that surpasses knowledge. And as Paul writes, we do so in order that we "may be filled with all the fullness of God." So in these verses Paul unfolds for us a very precise and yet very thorough look at the Holy Spirit's work in the lives of believers. The Spirit strengthens us in our inner beings (v.16), and in doing so kindles a loving faith in our hearts, roots and grounds us in love, (v. 17), gives us a comprehension of the God who is incomprehensible (v.18), teaches us how dearly we are loved by Christ (and by extension, by God through Christ), and in all of this fills us with all the fullness of God (v.19). If we are thinking of the Holy Spirit's work purely in terms of "gifts of the spirit" (such as tongues, prophecies, healings, and so on) as many Christians today seem to do, we are missing what the bible says is the most important thing the Spirit does - that it generates in our souls a life of faith and a knowledge of the eternal God who loves us and sent his Son to die for our sins. Faith is a miracle of the Spirit; salvation is a miracle of the Spirit; love of God and neighbor are miracles of the Spirit, and these are infinitely more important than the ability to speak in a tongue or to touch someone and heal a disease, as good as those are. When a Christian looks into his own soul and perceives faith in God there, that Christian is sensing nothing less than the presence of the Holy Spirit in his life. How small a view of the Spirit we have if we think that it is only with us at times when we are working miracles!
For Paul in this passage it is not about the power we think we can work, but it is about "the power at work within us," (v.20) the power of God who through the Holy Spirit creates in our hearts the flame of love for God and his creation. Do you, if you are a Christian, realize how reassuring it is that God's power is at work within us, and is that something in which you trust? If you are reading this and you are not a Christian, have you ever given any thought to what is the deepest motivating force in your life? I invite you, if you do not believe in Jesus Christ, to consider Paul's prayer for the churches of Ephesus, how he describes the working of God's power in the lives of believers. That same power may well be at work in you, and may God give you grace to receive Christ, and find in him "boldness and access with confidence through our faith in him" (v.12) - boldness with confidence to live in the presence of the God who created the universe with love and joy. "Now to him who is able to do far more abundantly than all that we ask or think, according to the power at work within us, to him be glory in the Church and in Christ Jesus throughout all generations, forever and ever. Amen." (Eph.3:20-21)