Therefore, I urge you, brothers, in view of God's mercy, to offer your bodies as living sacrifices, holy and pleasing to God—this is your spiritual act of worship. Romans 12:1
Maturing Christians develop a habit of constantly presenting the body to God in holy obedience. The human body is a stunning masterpiece of God’s creative power. David said, “I praise you because I am fearfully and wonderfully made” (Psalm 139:14). It is by the body that we can do a lifetime of good works that advance the two journeys—our own personal holiness and the spread of the gospel of Christ. But scripture also reveals that the body is a battleground over which sin and grace fight every single day. Galatians 5:17 says the desires of the flesh and the yearnings of the Spirit are at war with each other, and at every moment whichever controls the body will produce fruit for either life or death. So, Christian sanctification ultimately displays itself in action - the deeds of the body. And the first action a maturing Christian must take continually is the presentation of the body to God as a living sacrifice.
"To offer our bodies to God as a living sacrifice is like a soldier reporting to his general for orders."
When Paul wrote the phrase “living sacrifice,” he was drawing on centuries of lessons from the animal sacrificial system that was the heart of the Old Covenant. Though Christ’s death on the cross ended that system forever, its lessons remain powerfully active. Sacrifice is something valuable offered to God. An animal could only be offered once, and it was always dead when it was offered. The priest would pour out its blood and burn up its flesh on the altar fire. But God is calling Christians to make a continual, living sacrifice of their physical bodies to him in holy obedience. This command in Romans 12:1 is a simple restatement of the teaching he developed fully in Romans 6 in which he commanded Christians to stop offering ourselves in slavery to sin and the parts of our bodies as instruments of wickedness. Instead, we are to offer ourselves in slavery to God and the parts of our bodies to him as instruments (tools or weapons) of righteousness (Romans 6:13). The word “present” or “offer” is the essence of sacrifice, but it is also a military term—as a soldier reporting to a commanding officer for duty. Essential to this image is obedience; to offer our bodies to God as a living sacrifice is like a soldier reporting to his general for orders. This mentality of continual obedience is essential to all the holy actions of the body that follow.
All godly actions are done in obedience to Christ. We are not called on to innovate new works that God never commanded us. We are to fit into what he is doing in the world as obedient soldiers or faithful slaves. And habitual obedience is what the Lord demands of us. We are not our own, we have been bought with the price of Christ’s blood. All of this is factually and eternally true. But God still wants us to realize it moment by moment, and to make a delighted choice to serve him.
So, practically, every day should begin with a maturing Christian coming to God in prayer and saying, “Lord, I am yours. You created me and you redeemed me. I belong to you forevermore. But especially today, I recognize your kingly rule over my life. I offer my body to you now. I yearn to serve you every moment of this day. For your glory and the spread of the gospel of Christ.” Then, having done that at the beginning of the day, renew it as often as we think of it, moment by moment. That’s what a “living sacrifice” is and a river of good works follows.