But as He who called you is holy, you also be holy in all your conduct, because it is written, “Be holy, for I am holy.” (1 Pet 1:15-16)
God is holy and we should also be holy in all our conduct. The basic idea of holiness in the Bible is separation from all that is profane. In Leviticus, God was concerned with the ritual of the sacrificial system as well as with ethical requirements. The biblical distinction between “clean” and “unclean” is the way God designated the difference between what He could receive into His presence and what must remain apart from Him. Only people, animals, and objects designated as clean could enter the tabernacle, and later the temple, as part of the worship of God. Specific rituals were instituted by God for making an “unclean” person or object “clean”. The designation of “clean” and “unclean” also implies a distinction between ethical character and behavior that is acceptable to God from that which is unacceptable.
In the Old Testament, the word “holiness” is a dedicated terminology for sacrificial rites, pointing to two levels of meaning: purification rituals and consecration to God. The New Testament also inherits these two levels of meaning from the Old Testament: purity and consecration to God. In his teachings, Paul quoted the special terminology of Old Testament rituals, pointing out that people should dedicate themselves to God and serve Him (Rom 15:16). In his Epistle, Peter applies it in accordance with the basic principle of living in a way that is appropriate for God’s people. For example, Peter advised, “Do not let your adornment be merely outward–arranging the hair, wearing gold, or putting on fine apparel–rather let it be the hidden person of the heart, with the incorruptible beauty of a gentle and quiet spirit, which is very precious in the sight of God.” (1 Pet 3:3-4)
“Give unto the LORD the glory due to His name; Worship the LORD in the beauty of holiness.” (Ps 29:2)
The fact that there is so much about sacrifice in the Old Testament tells us just how significant the sacrifice of Jesus is for us. In gratitude for all that God has done for us by the sacrifice of Jesus on our behalf, we are to offer our bodies as a living sacrifice, holy and acceptable to God – this is our true and proper worship (Rom 12:1–2).