"14 For this reason I bow my knees before the Father, 15 from whom every family in heaven and on earth is named, 16 that according to the riches of his glory he may grant you to be strengthened with power through his Spirit in your inner being,17 so that Christ may dwell in your hearts through faith—that you, being rooted and grounded in love, 18 may have strength to comprehend with all the saints what is the breadth and length and height and depth, 19 and to know the love of Christ that surpasses knowledge, that you may be filled with all the fullness of God.
20 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, 21 to him be glory in the church and in Christ Jesus throughout all generations, forever and ever. Amen."
Ephesians 3:14-21
The words 'that Christ might dwell in our hearts by faith' in 17 need to be understood in the context of what Paul has said in 2:22 about being 'an habitation of God through the Spirit'. It might be thought that to pray thus is rather strange when in fact we are already 'an habitation of God'. But we need to understand Paul's meaning thus: he invariably uses indicatives to express the wealth of our position in Christ: 'This is what you are' he means, 'and I pray you will realise this in your experience, that His indwelling, and your being an habitation of God will be a glorious reality to you and that you may indeed prove what a wonderful thing this is' (this is similar, and for the same reasons, to what he says later in 5:18 about being 'filled with the Spirit', which means in effect 'let His gracious indwelling in you be all that it was designed by God to be')! The phrase 'rooted and grounded in love' speaks of the inner stability and steadfast immovability that is the hallmark of mature and stable Christian experience. One thinks of the lines of the old gospel hymn
'Fastened to the rock which cannot move,
Grounded firm and deep in the Saviour's love'
for when Christ dwells in our hearts by faith it is essentially and inevitably a loving relationship that fills our experience, for He is love!