Reflecting on Ephesians 3:14-19, German Reformed theologian and pastor Wolfgang Musculus (1497-1563) draws out the significance of Christ’s indwelling for the nurture of believers. Musculus understands indwelling as our union with Christ as a body of believers, and argues that this relationship is the same as a branch grafted into a vine, from which it receives nurture and sustenance.
We Dwell in Christ
It may be asked how Christ dwells in the hearts of believers by faith. If we are said to dwell in Christ by faith, it is easy to understand why Paul says that we must cling to him in faith. But when he says that Christ dwells in our hearts by faith, it is hard to see what he means because faith is ours to begin with. Yet there is nothing obscure about the fact that he dwells in our hearts by faith. Does the faith that is in our hearts take the place of the indwelling of Christ when he is said to dwell in us by it? In fact it is better to understand this as referring to our indwelling in Christ, to whom we have been joined in one body, than to Christ’s dwelling in us. In other words, what this means is simply that Christ dwells in our hearts by his Spirit and by his grace.
If you say that a vine dwells in the marrow of its branches by its vital sap and power to grow, with which it gives those branches life, feeds them, nurtures them and makes them fruitful and does the same for those who have been grafted into it, then this will be easier to understand. In the same way Christ dwells in our hearts by his Spirit, by our faith through which we have been grafted into him and made partakers of his Spirit, by whom we are given life, fed, regenerated, ruled and strengthened. By faith we conceive Christ in our hearts, and so he dwells in us by faith.
Commentary on Ephesians 3:14-19.
Galatians, Ephesians, ed. Gerald L. Bray. Reformation Commentary on Scripture, NT vol. X, p. 321