When the word of God says, "Be perfect," it means exactly what it says (Matt. 5:48; James 1:4; Heb. 12:23). But how can we be perfect? First of all, let’s realize that Jesus Christ was perfect, as His heavenly Father is perfect. He did the Father’s Will instead of His own (John 6:38). That is what made Him perfect. He kept the Father’s sayings and He lived exactly as He saw the Father live. Anyone who lives as God lives will suffer persecution, so Christ suffered persecution (2 Tim. 3:12).
The Bible commands, "Discipline yourself for the purpose of godliness" (1 Tim. 4:7). How do you do that? Keep God’s Ways and do God’s Will on earth as it is done in heaven (Matt. 6:10). Psalm 145:17 says, "The Lord is righteous in all His Ways, and kind in all His deeds." Then, it stands to reason that a disciple of Jesus Christ should strive to be righteous in all his ways and kind in all his deeds.
If you know Jesus Christ was righteous, you know that everyone who practices righteousness is truly born of Him (1 John 2:29). And this is the key! When you practice righteousness, you are righteous in God’s eyes (1 John 3:7). You have begun the godly process that allows God the Father to make you perfect (Heb. 12:23).
By doing good deeds for God, you are practicing the truth that is according to godliness (Titus 3:8; 1:1; John 3:21). You have nothing to worry about now because you are a doer of the word as well as a servant of God (James 1:22; 1 Peter 3:13).
Very few people know that the word "perfect" used in Matthew 5:48 and Philippians 3:15 means "spiritually mature." Spiritually mature disciples do not practice sin in their lives. Instead, they overcome sin and its temptations by continually doing good for God.
No one who is truly born of God practices sin any longer in his life; and because he is born of God and God’s Spirit (seed) abides in him, he cannot sin (1 John 3:9). Those who belong to Jesus Christ have crucified the flesh with its evil practices and desires (Gal. 5:24). With the help of God’s Spirit, they put to death the things in their lives that are not pleasing to God (Rom. 8:13).
Now, they walk in the Spirit and no longer carry out the evil passions they once had (Gal. 5:16). Jesus crushed Satan’s nature in them, with their help, and now they are new creations with His nature formed in them (Rom. 16:20; Gal. 4:19; 6:15). They are now perfect or complete (2 Cor. 13:9, 11). They are spiritually mature. They are truly born again and the evil one does not touch them (1 John 5:18). They have overcome the evil one (1 John 2:13-14). They are perfect because God has perfected them.