The law is not our guide. True holiness comes without the law. The strength and rule for holiness are by the Word, walking in the Spirit.
Should one be found at fault, the Christian's work is to restore such, not criticize, in the spirit of meekness, lest he fall himself. Public, outward sin is not the question here. To bear one another's burdens is our privilege.
There were those who sought to lead the believers back to the law and made something of themselves. Such deceive themselves. Those in the assembly who are taught should support the servants who teach them; they also should have a special consideration for the saints in need. What a privilege to show out Christianity in a practical way by doing good.
There is a universal law which applies to all, believers or unbelievers. "Be not deceived; God is not mocked: for whatsoever a man soweth, that shall he also reap." To sow to the flesh is corruption, but they that sow to the Spirit shall of the Spirit reap life everlasting. To pretend to be a Christian and walk after the flesh is to mock God.
Paul was careful of his writing letters, as they were being inspired by God and he signed them with his own hand, although others usually wrote for him.
Paul returned to the subject of his letter, that there were some who would include the law with grace. Those Jews who wanted the saints to be circumcised would benefit because they would escape persecution, for the world will accept the doctrine of law but not of grace. The reproach of the cross was the life of Christianity. The cross tells what man is and what God is.
In Paul's eyes the One who was upon the cross was great. To believe in a crucified Christ overcomes the world. The apostle suffered greatly for the truth; his words showed who was his Master. His right as a servant of God should no more be questioned.
For those in Christ Jesus, neither the law nor the flesh avails in any way. There must be a new creature. Those who follow this rule find mercy and peace, as does the Israel of God. The Israel of God are those who, out of Israel, put their whole belief in Christ Jesus, without following the law, once Jews but now safe in Christ Jesus.