In (Romans 12:1), Paul says, "I beseech you therefore, brothers, by the mercies of God to present your bodies a living sacrifice, holy, pleasing to God, which is your reasonable service." Paul's admonition to the believers in Rome was to sacrifice themselves to God, not as a sacrifice on the altar, as the Mosaic Law required the sacrifice of animals, but as a living sacrifice. The dictionary defines sacrifice as "anything consecrated and offered to God." As believers, how do we consecrate and offer ourselves to God as a living sacrifice?
Under the Old Covenant, God accepted the sacrifices of animals. But these were just a foreshadowing of the sacrifice of the Lamb of God, Jesus Christ. Because of His ultimate, once-for-all-time sacrifice on the cross, the Old Testament sacrifices became obsolete and are no longer of any effect (Hebrews 9:11-12). For those who are in Christ by virtue of saving faith, the only acceptable worship is to offer ourselves completely to the Lord. Under God's control, the believer's yet-unredeemed body can and must be yielded to Him as an instrument of righteousness (Romans 6:12-13; 8:11-13). In view of the ultimate sacrifice of Jesus for us, this is only "reasonable."
What does a living sacrifice look like in the practical sense? The following verse (Romans 12:2) helps us to understand. We are a living sacrifice for God by not being conformed to this world. The world is defined for us in (1 John 2:15-16) as the lust of the flesh, the lust of the eyes, and the pride of life. All that the world has to offer can be reduced to these three things. The lust of the flesh includes everything that appeals to our appetites and involves excessive desires for food, drink, sex, and anything else that satisfies physical needs. Lust of the eyes mostly involves materialism, coveting whatever we see that we don't have and envying those who have what we want. The pride of life is defined by any ambition for that which puffs us up and puts us on the throne of our own lives.
How can believers NOT be conformed to the world? By being "transformed by the renewing of our minds." We do this primarily through the power of God's Word to transform us. We need to hear (Romans 10:17), read (Revelation 1:3), study (Acts 17:11), memorize (Psalm 119:9-11), and meditate on (Psalm 1:2-3) Scripture. The Word of God, ministered in our hearts by the Holy Spirit, is the only power on earth that can transform us from worldliness to true spirituality. In fact, it is all we need to be made "complete, thoroughly equipped for every good work" (2 Timothy 3:16 NKJV). The result is that we will be "able to test and approve what God's will is—his good, pleasing and perfect will" (Romans 12:2). It is the will of God for every believer to be a living sacrifice for Jesus Christ.