Paul's exhortation is especially interesting in light of what precedes it. Chapter 11 concludes a lengthy dissertation on the doctrinal foundation of Christianity, showing the central importance of faith and grace. Instruction in the practical aspect of Christianity begins with chapter 12. The two sections are linked by the word "therefore." By this, Paul demonstrates that Christian living is inseparably bound to Christian belief. Faith without works is dead, and works without the correct belief system is vanity. Wrong thinking cannot lead to right doing.
If a person drinks in the spirit of Paul's doctrinal teaching in the first eleven chapters, he will present his body a living sacrifice and renew the spirit of his mind. Thus, outwardly and inwardly he will be on his way toward God's ideal for human conduct. All the virtues produced from this change will begin to grow and manifest themselves in his life. Self-surrender and its companion, self-control, are inseparable parts of this command.
Paul uses the metaphor of sacrifice throughout verse 1 to reinforce both similarities with and contrasts between Israel's Old Covenant sacrificial system and the Christian's sacrifice of His life in service to God. "Present" is a technical expression from the sacrificial terminology. Under the Old Covenant, the offerer's gift was presented to God and became His property. Similarly, the gift of our life is set apart for God's use as He determines. When we are bought with a price, we belong to ourselves no longer.
The Old Covenant sacrifices produced a sweet smell that God declares in Leviticus 1:17; 2:2; and 3:5 to be a fragrant aroma in His nostrils. In the same way, the gift of our life is "acceptable to God." Then Paul says that giving our lives in this way is "reasonable," that is, of sound judgment, moderate, sensible, or as many modern translations say, rational or spiritual. The outward acts of a son of God spring logically from what has changed in the inner man. His mind is being renewed, and he is thus controlling himself to live according to God's will rather than in conformity to the insanity of this world.
The last word in verse 1, "service," is as important as any, for within this context it describes the service, not of a domestic slave, but of a priest in complete self-surrender performing his duties before God's altar (I Peter 2:5). It means that we must, first of all, be priests by our inward consecration and then we must lay our outward life on the altar in God's service. This is what our works accomplish.
Almost from the beginning of the Bible, sacrifice is one of the great keywords of God's way. God clearly alludes to Christ's sacrifice in Genesis 3, and the first sacrifices occur in Genesis 4. The principle of sacrifice is then woven into the fabric of virtually every book until beginning with Christ, the Founder of Christianity, it becomes perhaps the master-word for the outward life of His followers.
Sacrifices are inherently costly to the giver, or there is no real sacrifice in the offering. David explains in II Samuel 24:24, "Then the king said to Araunah, 'No, but I will surely buy it from you for a price; nor will I offer burnt offerings to the Lord my God with that which costs me nothing.'" Jesus amplifies this principle with a statement of far reaching day-to-day consequences: "Greater love has no one than this, than to lay down one's life for his friends" (John 15:13). What could be more costly than a person giving his life in service by living a way of the very highest of standards that his mind and body do not by nature and habit want to live? It requires a decision that will from time to time bring intense pressure upon him to control himself against strong drives to go in an entirely different direction. But he must control himself if he is to work in the service of God.