Good theology is always practical theology, for true faith in the Lord is not mere intellectual assent to the truths of the Bible but a living trust in Christ alone that bears fruit in service to God and neighbor (James 2:14–26). The structure of Paul’s epistle to the Romans bears this out. Having plumbed the depths of justification, sanctification, election, the place of Israel in God’s plan, and many other doctrinal topics in chapters 1–11, the Apostle does not simply end his letter. Instead, he moves on to more practical concerns, exploring what it means to live as followers of Christ in this world. Romans 12:1, therefore, is a transition point where Paul shifts his emphasis from the doctrinal to the ethical.
This shift in emphasis does not mean that Paul separates the ethical from the doctrinal. Indeed, he has already discussed ethics in the midst of his doctrinal exposition (Rom. 6:12–19), and he will include more doctrine in his presentation of Christian living (for example, 14:10b–11). Furthermore, we see the close connection of doctrine and ethics in today’s passage. The Apostle grounds His appeal for all that follows, including his ethical teaching, in “the mercies of God” (12:1). By this phrase, Paul reminds us of the source and sustenance of discipleship, namely, the mercy of the Lord in justifying us in Christ alone and in pouring out His Spirit upon us. Christian discipleship is finally based not on our own efforts, as important as they are in our sanctification, but rather on the salvation that Jesus has purchased for us and that the Spirit applies to us. In other words, as Dr. R.C. Sproul writes in his commentary Romans, Christ “gave himself for us, and we are to respond by giving ourselves to him…. We give ourselves to thank and serve him.”
Paul uses sacrificial imagery to describe our fundamental manner of serving God. We are to present ourselves to our Creator as “living sacrifices.” This somewhat paradoxical statement emphasizes total commitment to our Lord. Ordinarily, a sacrifice is something that is dead, and once it is consumed, it is set aside. A living sacrifice, on the other hand, is never set aside. There is no point at which it ceases to be an offering unto God. This, then, is the Christian life—in gratitude for our great salvation, we dedicate ourselves wholeheartedly and unreservedly to the Lord for the sake of His glory.