v1: Restoring the sinner; the reference here is not to deliberate or habitual sin. The person caught up (or overtaken) needs restoration, not rebuke, contrast 1 Cor 5.11.
There is need for discernment, to identify the problem correctly. And, if we are to restore others, we must be spiritual, we must exercise a spirit of gentleness, and consider ourselves, so that we are not tempted also. Compare also Jude 22-23.
v2: Where something weighs down or hinders another, we are to bear those burdens. The word used here means a load which is to be carried, and then put down. God has designed human beings both to be a burden and to carry the burdens of others.
v3-5: Personal responsibility and accountability. We are not to exalt ourselves, for that is self-deception. We cannot live another person's life, 1 Cor 3.11-15, for each one is personally accountable before God, Rom 14.10,12. We should not compare ourselves with others, for they serve the same Master.
We must examine ourselves; negative self-criticism and introspection are not helpful.
v6: The teacher is a recognised role within the church; it is a specific spiritual gift. The teacher continues to learn, and must remain humble and teachable. Similarly, those who are taught should share those things they have learned, so teacher and those taught are encouraged together.
v7-8: There are consequences of how we live, Ps 78.29; we have a continuing choice, to sow to the flesh or to sow to the Spirit. God is not deceived, for we may try to justify our disobedience; we cannot avoid the consequences of wrong-doing.
v9-10: There is resistance from the enemy, to hinder us from doing good. We must take every opportunity to do good and to carry on doing so. Our special responsibility is to care for fellow believers.
v11: Paul closed his letter with a personal comment. His normal practice was to dictate letters to another, but to write his own greeting, see Rom 16.22; 1 Cor 16.21; Col 4.18.
v12-16: Error is best opposed by a declaration of truth.
By teaching a different message, the Judaizers sought to avoid being persecuting for Christ's sake. The new creation is evidenced by faith expressing itself through love (5.6); how different is the character of the natural man, who promotes circumcision, "that they may boast about your flesh", see 4.17.
Paul's boast is in the cross of Jesus Christ. As a result, there is "new creation," and there is "peace and mercy." He boasted in the only true message. Paul's boast is not in the cross in a sentimental or nostalgic way, but in 'a powerful, life-changing experience dealing the death-blow to any world-based expectations and aspirations that he might have had, including his reputation.' (Terry Virgo, God's Lavish Grace, p109).
v17-18: Paul was spiritual, boasting in the cross of Christ, enjoying the grace of the Lord Jesus Christ in his spirit, but bearing the marks of persecution in his body.
His prayer is simply that his readers similarly enjoy the grace of the Lord.