To be properly understood this verse must be seen in its overall context. Paul is explaining to the Galatians how they have spiritually regressed by allowing certain brethren to convince them that they had to practice Judaism to be justified (Galatians 3:1-9). On the contrary, he argues, we are justified by faith in the sacrifice of Jesus Christ—that is, God wipes the record of our sins clean because of our belief in and commitment to Christ as our personal Savior (verses 11-14).
The question arises, then, what purpose is the law, specifically the Jewish law, often called the Old Covenant (verse 19)? His answer is that this law was a guide and a guard to restrain and preserve God's chosen people until Messiah came to reveal the gospel and the process of salvation (verses 23-25). That covenant, the tutor that brought us to Christ, is now passing away, no longer needed by God's begotten children, who have made a better covenant founded on better promises (Hebrews 8:7-13; see Galatians 4:21-31).
Christians, then, have no need to practice Old Covenant rituals, the chief of which was the sign of the covenant, circumcision. All Israelite males entered the Old Covenant by being circumcised on the eighth day of their lives (Genesis 17:9-14; Leviticus 12:1-3). This obligated them to keep the whole covenant—all the laws and rituals contained in it—for only by observing every detail of it could an Israelite hope to conform to it. Thus, if a Christian thinks he can be righteous before God by observing Old Covenant practices, he must go the whole nine yards: tassels on his garments, phylacteries, washings, etc.!
Paul says that there is no justification before God even if one should do all these things! Notice Galatians 5:6: "For in Christ Jesus neither circumcision nor uncircumcision avails anything, but faith working through love [avails]." Only by faith in Christ Jesus is a person justified. We are saved by grace through faith, not by works (Ephesians 2:8-9). Once we are justified, however, God's spiritual law—codified principles of God's love (John 14:15; I John 5:2-3)—becomes our guide to acceptable Christian behavior (Romans 7:7, 12, 24-25; 13:8-10; I Corinthians 7:19; James 1:21-27; etc.).
Saved By Faith Alone?
Was God's Law Nailed to the Cross?
What Was the Law 'Added Because of Transgressions'?
Forms vs. Spirituality (Part 5)
Forms vs. Spirituality (Part 6)
The Covenants, Grace, and Law (Part Four)
The Covenants, Grace, and Law (Part Six)
Why We Must Put Out Leaven
The Christian Fight (Part Four)