Definition and Concept:
Being set apart, often referred to as sanctification, is a central theme in the Bible that denotes the act of being made holy or consecrated for a specific purpose. This concept is deeply rooted in the nature of God and His relationship with His people. In the biblical context, to be set apart is to be distinguished from the ordinary or profane and dedicated to God's service and glory.

Old Testament Context:
In the Old Testament, the idea of being set apart is first introduced with the nation of Israel. God chose Israel to be a holy nation, distinct from other peoples. In Leviticus 20:26 , God declares, "You are to be holy to Me because I, the LORD, am holy, and I have set you apart from the nations to be My own." This setting apart was not only a matter of identity but also involved living according to God's laws and commandments.

The priesthood, particularly the Levites, were also set apart for service in the tabernacle and later the temple. Exodus 28:3 speaks of the garments made for Aaron, the high priest, "to consecrate him, so that he may serve Me as priest." The consecration of the priests involved rituals and sacrifices that symbolized purification and dedication to God.

New Testament Context:
In the New Testament, the concept of being set apart is expanded to include all believers in Christ. The apostle Paul frequently addresses the sanctification of believers, emphasizing that it is both a positional and progressive reality. In 1 Corinthians 1:2 , Paul writes, "To the church of God in Corinth, to those sanctified in Christ Jesus and called to be saints, together with all those everywhere who call on the name of our Lord Jesus Christ."

Believers are set apart through their union with Christ, who is the ultimate example of holiness. This sanctification is initiated by the Holy Spirit, who indwells believers and empowers them to live lives that reflect God's holiness. Romans 8:9 states, "You, however, are controlled not by the flesh, but by the Spirit, if the Spirit of God lives in you."

Practical Implications:
Being set apart has practical implications for the life of a believer. It involves a call to live differently from the world, pursuing righteousness and holiness. In 1 Peter 1:15-16 , believers are exhorted, "But just as He who called you is holy, so be holy in all you do, for it is written: 'Be holy, because I am holy.'"

This call to holiness is not merely about external behavior but involves a transformation of the heart and mind. Romans 12:2 urges believers, "Do not be conformed to this world, but be transformed by the renewing of your mind." This transformation is a lifelong process, as believers grow in their relationship with God and become more like Christ.

Conclusion:
The biblical concept of being set apart underscores the distinctiveness of God's people and their calling to live in a manner that honors Him. It is a divine initiative that requires human response, as believers are called to cooperate with the Holy Spirit in the process of sanctification. Through this, they bear witness to the holiness of God in a world that is often contrary to His ways.