When the apostle Paul said, "And I testify again to every man who becomes circumcised that he is a debtor to keep the whole law" (Galatians 5:3), was he implying that the gentiles' exemption from physical circumcision also exempted them from having to obey any of the laws of God?
That is what is commonly taught concerning this passage. But that is not what Paul meant! The laws of the Sinai Covenant varied greatly in their purpose and content. Some laws defined sin—spelled out transgressions. These laws, though included as part of the Sinai Covenant, neither commenced at Sinai nor ended at Jesus Christ's crucifixion.
Other laws included as part of the Sinai Covenant established administrative procedures and penalties for disobedience. They were necessary for the governing of the nation of Israel.
Still others—such as circumcision and sacrifices—had a symbolic purpose. The book of Hebrews explains that, for the most part, those types of laws had only a temporary purpose because they were "concerned only with foods and drinks, various washings, and fleshly ordinances imposed until the time of reformation" (Hebrews 9:9-10). But Hebrews does not say that everything contained in "the whole law" was temporary.
Paul's point in Galatians about being "a debtor to keep the whole law" is expressed in the context of those who wanted to impose circumcision on the Galatians. Their reasoning implied, maybe even unintentionally, that at least some of the symbolic aspects of the law would be required of the gentiles. That is the false teaching against which Paul forcefully argues in his epistle to the Galatians.
Because of His perfect obedience, Jesus Christ was qualified to lay down His own life so as to free from enslavement to sin and its death penalty all who have faith in Him. So Paul reasons with the Galatians: "And I, brethren, if I still preach circumcision, why do I still suffer persecution? Then the offense of the cross [the preaching that Jesus Christ is our sacrifice for sin] has ceased" (Galatians 5:11).
His point is that demanding that the symbolic ritual of circumcision be required is a denial of the sufficiency of Christ's sacrifice and work. He rejected that argument—but he did not reject the whole law.
God's commandments that define sin are written in "the law"—but they don't make up the whole law. Paul used the term "the whole law" to make it clear that the law has within it symbolic aspects that should not be required of the gentiles.
Paul expresses clearly, in a letter to the Corinthians, this distinction in what the gentiles should keep from what was not necessary: "Circumcision is nothing and uncircumcision is nothing, but keeping the commandments of God is what matters" (1 Corinthians 7:19).