The two-fold letter of Ephesians is neatly structured giving theology and practice even billing. The former section (Chapters 1 – 3) commences and concludes with prayerful language and these prayers are some of the most inspiring Scripture there is.
Ephesians 1:15-23 is very much about how church should be; the broader context of living, loving fellowship with humankind, especially regarding the meeting of the saved, as far as possible. The prayer effectively locates this for us.
In many ways the prayer discourse in 1:15-23 continues, or at least links with, 3:14-21, but the latter finishes with punchy, inspiring crescendo.
It would be hard to pack in so much meaning into so few words as there is in Ephesians 3:14-21. To hear these words read aloud would inspire the flattest of hosts. Paul kneels humbly in reverence. He prays the Ephesians might be lavished in power through their ‘inner being,’ and that Christ might truly “dwell” in their hearts through faith. (“Colonise” might be a good alternative word). Christ is to ‘take up residence’ in us. This ‘in power’ theology has tremendous meaning. All of it has. Christ dwelling in our hearts is situational; the method achieving same is through faith. These depend on each other. Grasping (comprehending) how vast the love of Christ is—an immeasurable, uncontainable and indescribable love—is but a hope. Again, we know it by faith. We cannot plumb the depths, climb the heights or travel the width or breadth of it. Such safety we have in his all-surpassing love. Paul prays the Ephesians would be truly filled brimming with the ‘glorious riches’ of God.
This power that works in and through us—a power that surpasses all knowledge and understanding—is living and real and, in the person of Jesus, is ‘able to do immeasurably more than all we ask or [even] imagine.’
It’s a power to consistently rely upon if we can only hold onto it in purity of faith.
© 2010 S. J. Wickham.
 Klyne Snodgrass, Ephesians – NIV Application Commentary (Grand Rapids, Michigan: Zondervan, 1996), p. 87-89.