When in contact with a sinful world, the Old Testament has shown that God sanctifies everything with His glory before He comes in contact with it (Ex 3:5; 19:23; 40:32-38). Everything must be morally pure, set apart and devoted to Him before God, as a theosophany, would dwell among His people (Ex 29:43-46). Failure to be sanctified properly meant instant death for anyone who came into the presence of the holy God (Lev 16:1-4).

Because the nation of Israel committed themselves to be God's people and His own possession, they were to sanctify themselves; this was only possible because God was the Lord who makes them holy (Lev 20:7).

The Law of Moses was intended to teach the nation of Israel of what it meant to "be set apart" and the procedures of how to be set apart. God repeatedly encourages the Israelites to "be holy, because He is holy" (Lev 11:44-45; 19:2; 20:26; 21:8). But Israel failed to understand the righteousness intended behind the legislation (Deut 31:14-22; 32:1-47).

When Jesus begins His public ministry and reveals that the Law and Scriptures point to Him and Himself as their fulfillment, He elaborates on the Law and the meaning of holiness (Matt 5:17-48). He presents contrasts, "you have heard…, but I tell you...," as a means to teach the ethics of being set apart. He contrasts anger with reconciliation (Matt 5:21-26), adultery and purity (Matt 5:27-30), divorce and remarriage (Matt 5:31-32), promises and truthfulness (Matt 5:33-37), personal injury and self sacrifice (Matt 5:38-42) and hatred and love (Matt 5:43-47).

The contrasts show that the Jews' approach to the Law lost its demand for holiness; understood properly, the Law reflected the holy perfection of God.

For disciples, set apart for God, Jesus demands that they "be perfect, as your heavenly Father is perfect" (Matt 5:48) in moral purity in thought and action. The apostle Peter would remind Believers, saved through the gospel call of Jesus, to be obedient to God of the Scriptures in a similar manner, "be holy, because God is holy" (1 Pet 1:13-16; Lev 11:44-45; 19:2; 20:26).

Just as the nation of Israel was set apart as God's people, Jesus indicates that the Messianic community carries on this same distinction. Then as now, God works to sanctify His people.

From a legal perspective, God sanctifies man with two provisions:

The Law of Moses taught what sin was (Rom 3:19-20; 7:7-8) and revealed God's code of moral and spiritual behavior; Jesus considered this eternal and immutable (Matt 5:18). As a covenant by which man atones for his sins to keep God's favor, Paul tells us that this function has ended (Gal 3:19).

The New Covenant provided absolute and complete forgiveness of sin, sanctification without human merit or works, and was internal ("I will put My law within them an on their heart" – Jer 31:33) and not subject to human interpretation.

The New Covenant was made, because the nation of Israel broke the Law of Moses and failed to set themselves apart as God's own people (Jer 31:32).

Both provisions share the same purpose: sanctifying people so that the Holy God can dwell among them (Ex 29:44-46; Lev 26:11-12). Thus, as God works to sanctify non-Believers, "that you may believe in Him whom He has sent" (John 6:29; 9:3), these provisions demonstrate a love that is rich, costly and extended even to enemies and without distinction other than being His good creation (Gen 1:26-31). This is the ultimate characteristic that Jesus exhorts His disciples to emulate, "be perfect, as your heavenly Father is perfect" (Matt 5:48).

Through the New Covenant, God has the legal means to continue His work of sanctification through a Believer's life. Because the New Covenant provides regeneration, regeneration itself validates adoption and establishes the legal rights and means to be children of God (John 1:9-13; Tit 3:4-7).

Thus when Jesus contrasts hatred and love (Matt 5:43-47) and provides God's example of causing the "sun to rise on evil and good, and sends rain on the righteous and the unrighteous," He uses the example as an incentive to be "sons of the Father in heaven."

To be a "son of the Father" requires a certain sonship where the Believer pursues a life lived in a way, separate and superior to the lifestyles around them, that is patterned on the character of God (Eph 5:1-10; 4:23-24; Col 3:5-11).

Sanctification is becoming something that the disciples are not yet – a son of God.

Because of regeneration, the apostle Paul sees Believers as God's children, and progression is towards children without fault (Philip 2:12-16). Because God wrote the Law upon the Believer's heart, the Believer knows what sin is and can work towards a life without sin cognizant of the implications of sin's presence before the holy God (Philip 2:12).

God works to sanctify Believers by providing Himself as an example, motivates Believers to be His children without fault and be pleasing to His sight (1 Thess 4:1; Heb 13:20-21).

God also works through His word, the Bible, so that Believers will be imitators of Him (1 Thess 2:13-14).

Because of regeneration, God accepts and treats Believers as His children (Heb 12:5-11).

Discipline includes the idea of rebuke and education (Heb 12:5-6).

God chastises to produce in Believers a character like His own; thus, the certainty of suffering is meant to be an encouragement (Heb 12:7, 10; James 1:2-4).

In God's eyes, illegitimate children are not heirs or members of His family; their freedom from discipline is because they are not privileged (Heb 12:8).

While a Believer strives against sin, God somehow has a hand in it and helps the Believer share in holiness and produce a "harvest of righteousness and peace" (Heb 12:10-11; 1 Cor 11:31-32).

As God sanctifies Believers, they reflect His moral character to the world and serve as His invitation of love to others to be His people (John 17:16-19).