God called the people of Israel "to be holy" because he freed them from slavery in Egypt (see Leviticus 11:45). He also freed humanity through Jesus Christ, who paid the price to release us from slavery to sin and death (1 Peter 1:18). God paid the ultimate price to set humanity free, redeeming us “with the precious blood of Christ, a lamb without blemish or spot” (1:19). Through this sacrifice, God has purchased our freedom from the empty way of life that people experience before coming to Christ.
Holiness was at the center of the lifestyle that God required from his people under the old covenant (the agreement God made with Israel through Moses at Mount Sinai). God commanded them to "Be holy because I, the LORD your God, am holy" (see Leviticus 19:2). God had rescued his people from the control of a cruel, foreign nation that worshiped other gods. Now they were to live as God's people in the new land where he was bringing them.
The apostle Peter applies this same requirement to God's people of the new covenant (the agreement God made through Jesus Christ). This includes all who have come to God through faith in Jesus Christ. Peter writes, "just as He who called you is holy, so be holy in all you do,” (1 Peter 1:15). This holiness has both a negative and a positive side.
Negatively, to be holy means to separate from this world. This means avoiding the ways of thinking and acting that are common among people who do not know God. We turn away from our old sinful lifestyle that we lived before becoming Christians. Because of their new identity in Christ, believers live as foreigners in this world (1 Peter 1:17). Their values are shaped by God's kingdom rather than earthly culture.
Positively, to be holy also means to be separate for God. This means we try to be like our Father in heaven and live according to the values of our new homeland, the kingdom of God.
Believers in Christ have been set free from the old, meaningless life and its values. We are to live as obedient children of our heavenly Father (1 Peter 1:14). Our Father has not only saved us because he loves us, but he also disciplines his children, just like a human father would. He will judge "each one’s work impartially" (1:17).
Therefore, we must live before God "in reverent fear" (1:17). We must acknowledge his holiness and majesty and strive by faith to reflect his holy character in our lives. Holiness is an essential part of the Christian life. While we are justified by faith, true faith naturally expresses itself in a life that reflects God's holiness (see James 2:14–26).
Passages for Further Study
Leviticus 10:3; 11:44–45; 19:2; Isaiah 29:17–24; 1 Corinthians 6:9–20; Hebrews 12:1–13; 1 Peter 1:15–18; Revelation 21:5–8; 22:14–15