Leviticus 20:26
And ye shall be holy unto me: for I the LORD am holy, and have severed you from other people, that ye should be mine. And ye shall be holy unto me: for I the LORD am holy, and have severed you from other people, that ye should be mine.
The Lord Himself is holy, and He has cut off Israel from the other nations to belong to Him as His own. Because He is holy, those He has thus set apart are to be holy to Him. This holiness is the sanctifying of the whole person into purity like Christ's and full agreement with God's will, so that He is honored in body and spirit. It is to be openly seen in loyalty to Christ and in keeping God's statutes, judgments and commandments in daily life with others. It therefore turns away from the evil ways, customs and fellowships of the world, standing apart in devoted service to God.
Holy God, Separated People
The Lord is holy, and He has severed His people Israel from other peoples to belong to Him as His own. That severing is a setting apart from others so that they are His, belonging to Him and to no other. Because He is holy, He calls His separated people to be holy unto Him. Their holiness rests on His holiness, so that to be His people entails being holy as He is holy.
That holiness is the sanctification of the whole being, purity like Christ's, and complete conformity to God's will. Being His people means living for Him and glorifying Him in body and spirit, since they belong to Him.
For Israel this holiness included physical cleanliness in God's presence. Before hearing Him proclaim the law at Sinai, the people had to wash themselves and their clothing. No impurity was permitted in His presence.
Living Holy and Separate
Belonging to God must be openly shown, for He has separated His people from others to be His own, and because He is holy they are to be holy unto Him. That belonging is allegiance to Christ made visible, with His mark appearing in the life in sanctified works. This holiness is expressed in keeping His statutes and judgments and in living by His commandments in dealings with others. To be His people entails keeping His commands as the practical form of being set apart to belong to Him.
The separation is shown by obedience to His commandments and by turning away from the evil practices of the world. Such obedience distinguishes those who serve God from those who do not. It means refusing worldly customs, habits, and sentiments, having no fellowship with the works of darkness, and standing distinct in devoted service as God's people. It calls for moral independence from the world, not binding themselves to it but trusting the Lord to complete His work.