Here (12:3-8) we get the first mention of Paul’s key image of the church as the Body of Christ, which he develops in different ways in different letters.
It’s part of a wider strand of his thought. Immediately before it, he’s appealed to the Roman Christians,
Do not be conformed to this world, but be transformed by the renewing of your minds, so that you may discern what is the will of God—what is good and acceptable and perfect. (12:1-2)
Before that in turn, he’s reminded his readers that God’s ways are not the same as ours – that his purposes and wisdom are beyond our full understanding. And before that… the image of the Gentiles as wild branches grafted into the root stock of Israel.
If there’s a flow to the argument, it seems to be this – that faith is not an individualistic activity. We are saved as part of a community, both through history and around us in the church. The branches aren’t just grafted into Christ, as perhaps in John’s use of the true vine. They are grafted into the vine of God’s people Israel – and they depend for their life not only on the Holy Spirit but also upon being part of the great story of God’s faithfulness, reaching back to Abraham.
And within that stream of history, the church of the present day is part of our salvation, just as much as our historic roots. It is the expression of the life and body of Christ. Honest. It may not always look like that, but that’s the reality. We are saved and called to play our part in Christ’s work in the world, and each of us has a part to play which meshes with those of others, together to be Christ to the world in which we are set.
If that’s the case, then perhaps part of the renewing of our minds to which Paul calls us is the shift of vision from the indivdual to the shared vision of faith – to each finding our own, individual contribution to the faith, life and mission into which we’ve been called. Salvation and vocation go together. Individual faith and church life are two parts of the same thing.
To Paul, there’s no healthy Christian life that is lived alone. All discipleship is tied to being part of the renewed Israel, and to playing a part in the Body of Christ, the Church.