How should our identity in Christ affect the way we live?
Identity is defined as "the collective aspect of the set of characteristics by which a thing is definitively recognizable or known." If our identity is in Christ, we should display characteristics that are recognizable as belonging to Christ. The word "Christians" means "followers of Christ" and as the Apostle John points out, we should literally follow in His footsteps. "By this we may know that we are in him: whoever says he abides in him ought to walk in the same way in which he walked" (1 John 2:5b-6).
Scientists have proven the plasticity of the brain; the human mind tends to conform to the things to which it is continually exposed. Peace of mind is often dependent on the degree to which all the parts of a person—mind, spirit, emotions, body, will—are aligned. A believer's spirit is one with Christ—the old man has died and the new man lives in Him (Galatians 2:20). Because this oneness with God's spirit is eternal and predominant (Romans 8:37-39), the rest of the person must gradually come in line with Him. The flesh fights this assimilation, however. The Apostle Paul describes his own experience with this in Romans 7:14-25, saying "I delight in the law of God, in my inner being, but I see in my members another law waging war against the law of my mind and making me captive to the law of sin that dwells in my members" (v. 22-23). Christ's sacrifice for us made us holy, but that sanctification is exposed over time (Hebrews 10:10, 14). Sin robs us of our peace, but being in Christ means we have been saved from sin, and we no longer must live according to its whims (1 Corinthians 15:56-57; Romans 6:6-14). We will be happier, and more at peace, if we strive to walk as Jesus walked. Much of the writings of the New Testament are encouraging believers toward this goal.
Paul tells the Ephesians to no longer walk as the Gentiles do, in the "futility of their minds" and darkened understanding, but instead to "put off your old self" and "be renewed in the spirit of your minds, and to put on the new self, created after the likeness of God in true righteousness and holiness" (Ephesians 4:17-23). He tells the Galatians to "walk by the Spirit" instead of by the flesh, for the two are opposed to one another—the more a believer is led by the Spirit, the less power the flesh will have over him (Galatians 5:16-25). He encourages the Corinthians to make choices that will be for the spiritual good of themselves and also their neighbors, and to glorify God with their actions (1 Corinthians 10:23-33). He tells the Romans to present their bodies as a living sacrifice as an act of spiritual worship, saying "Do not be conformed to this world, but be transformed by the renewal of your mind, that by testing you may discern what is the will of God, what is good and acceptable and perfect" (Romans 12:1-2).
Identity in Christ is a direct result of faith in Christ, and that faith, or trust, should continue throughout the life of a Christian. No Christian comes into perfect alignment with the Spirit immediately, or easily. Trusting God means we live our lives in Him according to the revelation of Himself given in Scripture, and not according to our own understanding (Proverbs 3:5-8). We are saturated with the world every day, and it is important to remember that even though our identity is in Christ, we are still influenced by the world. Our minds are easily confused by its messages, and our emotions are easily swayed by what it offers. As Jesus said "the spirit indeed is willing, but the flesh is weak" (Matthew 26:41). That is why it is absolutely crucial that we let God lead us, by His Spirit and by the Word. "My son, do not forget my teaching, but let your heart keep my commandments, for length of days and years of life and peace they will add to you" (Proverbs 3:1-2).