Ephesians 3:17

That Christ may dwell in your hearts by faith
This is another petition put up by the apostle for the Ephesians, which is for the inhabitation of Christ in them: the inhabitant Christ is he who dwells in the highest heavens, who dwells in the Father, and the Father in him, in whom all fulness dwells, the fulness of the Godhead, and the fulness of grace; so that those in whose hearts he dwells cannot want any good thing, must be in the greatest safety, and enjoy the greatest comfort and pleasure; and this inhabitation of Christ prayed for is not to be understood in such sense, as he dwells everywhere, being the omnipresent God; or as he dwells in the human nature; nor of his dwelling merely by his Spirit, but of a personal indwelling of his; and which is an instance of his special grace: he dwells in his people, as a king in his palace, to rule and protect them, and as a master in his family to provide for them, and as their life to quicken them; it is in consequence of their union to him, and is expressive of their communion with him, and is perpetual; where he once takes up his residence, he never totally and finally departs: the place where he dwells is not their heads, nor their tongues, but their hearts; and this is where no good thing dwells but himself and his grace; and where sin dwells, and where he is often slighted, opposed, and rebelled against: the means by which he dwells is faith; which is not the bond of union to Christ, nor the cause of his being and dwelling in the hearts of his people; but is the instrument or means by which they receive him, and retain him, and by which they have communion with him:

that ye being rooted and grounded in love;
either in love to God, and one another; for faith and love go together; and love is sometimes weak, and needs establishing; and what serves to root and ground persons in it, are the discoveries of God's love, views of Christ's loveliness, the consideration of blessings received, and the communion they have with God, and Christ, and one another, and a larger insight into the doctrines of the Gospel: or rather in the love of God to them; which is the root and foundation of salvation; this is in itself immovable and immutable; but saints have not always the manifestations of it, and sometimes call it in question, and have need to be rooted and grounded in it; which is to have a lively sense of it, and to be persuaded of interest in it, and that nothing shall be able to separate from it.