This I say then. Now follows the remedy. The ruin of the church is no light evil, and whatever threatens it must be opposed with the most determined resistance. But how is this to be accomplished? By not permitting the flesh to rule in us, and by yielding ourselves to the direction of the Spirit of God. The Galatians are indirectly told, that they are carnal, destitute of the Spirit of God, and that the life which they lead is unworthy of Christians; for whence did their violent conduct towards each other proceed, but from their being guided by the lust of the flesh? This, he tells them, is an evidence that they do not walk according to the Spirit. Ye shall not fulfill. We ought to mark the word fulfill; by which he means, that, though the sons of God, so long as they groan under the burden of the flesh, are liable to commit sin, they are not its subjects or slaves, but make habitual opposition to its power. The spiritual man may be frequently assaulted by the lusts of the flesh, but fulfill them, -- he does not permit them to reign over him. -- On this subject, it will be proper to consult the eighth chapter of the Epistle to the Romans

This I say then - This is the true rule about overcoming the propensities of your carnal natures, and of avoiding the evils of strife and contention.
Walk - The Christian life is often represented as a journey, and the word walk, in the scripture, is often equivalent to live; Mark 7:5. See the notes at Romans 4:12; Romans 6:4, note; Romans 8:1, note.
In the Spirit - Live under the influences of the Holy Spirit; admit those influences fully into your hearts. Do not resist him, but yield to all his suggestions; see the note at Romans 8:1. What the Holy Spirit would produce, Paul states in Galatians 5:22-23. If a man would yield his heart to those influences, he would be able to overcome all his carnal propensities; and it is because he resists that Spirit, that he is ever overcome by the corrupt passions of his nature. Never was a better, a safer, or a more easy rule given to overcome our corrupt and sensual desires than that here furnished; compare notes, Romans 8:1-13.
And ye shall not fulfil - Margin, "Fulfil not" - as if it were a command. So Tyndale renders it. But the more common interpretation, as it is the more significant, is that adopted by our translators. Thus, it is not merely a command, it is the statement of an important and deeply interesting truth - that the only way to overcome the corrupt desires and propensities of our nature, is by submitting to the influences of the Holy Spirit. It is not by philosophy; it is not by mere resolutions to resist them; it is not by the force of education and laws; it is only by admitting into our souls the influence of religion, and yielding ourselves to the guidance of the Holy Spirit of God. If we live under the influences of that Spirit, we need not fear the power of the sensual and corrupt propensities of our nature.

Walk in the Spirit - Get back that Spirit of God which you have grieved and lost; take up that spiritual religion which you have abandoned.
Ye shall not fulfill the lust of the flesh - If the Spirit of God dwell in and rule your heart, the whole carnal mind will be destroyed; and then, not only carnal ordinances will be abandoned, but also the works and propensities of the flesh.

(15) [This] I say then, Walk in the Spirit, and ye shall not fulfil the lust of the flesh.
(15) He acknowledges the great weakness of the godly, because they are but in part regenerated: but he exhorts them to remember that they are endued with the Spirit of God, who has delivered them from the slavery of sin, and so from the Law, inasmuch as it is the power of sin, so that they should not give themselves to lusts.

This I say then, walk in the Spirit,.... The advice the apostle thinks fit to give, and which he would have observed, is, to "walk in the Spirit", that is, either after the Spirit of God; making the word inspired by him the rule of behaviour, which as it is the standard of faith, so of practice, and is the lamp unto our feet, and the light unto our path; taking him himself for a guide, who not only guides into all truth, but in the way of holiness and righteousness unto the land of uprightness; and depending upon his grace and strength for assistance throughout the whole of our walk and conversation: or in the exercise of the graces of the Spirit of God; as in the exercise of faith upon the person and grace of Christ, of which the Spirit is the author; and in love to God, Christ, and one another, which is a fruit of the Spirit; and in humility, lowliness of mind, meekness and condescension; all which is to walk in the Spirit, or spiritually, and strengthens the argument for love the apostle is upon: and this he encourages to by observing,
and ye shall not fulfil the lust of the flesh; he does not say there shall be no flesh, nor any lust of the flesh in them if they walk spiritually; or that the flesh should not act and operate in them; or that they should do no sinful action; all which is only true of Christ; and the contrary is to be found and observed in all true Christians, though ever so spiritual; but that they should not fulfil or perfect the lust of the flesh; should not give up themselves entirely to the power and dictates of the flesh, so as to be under it and at its command, and be obedient servants and slaves unto it; for, in this sense only, such that are spiritual do not, commit sin, they do not make a trade of it, it is not their constant employ or course of conversation.

If it be our care to act under the guidance and power of the blessed Spirit, though we may not be freed from the stirrings and oppositions of the corrupt nature which remains in us, it shall not have dominion over us. Believers are engaged in a conflict, in which they earnestly desire that grace may obtain full and speedy victory. And those who desire thus to give themselves up to be led by the Holy Spirit, are not under the law as a covenant of works, nor exposed to its awful curse. Their hatred of sin, and desires after holiness, show that they have a part in the salvation of the gospel. The works of the flesh are many and manifest. And these sins will shut men out of heaven. Yet what numbers, calling themselves Christians, live in these, and say they hope for heaven! The fruits of the Spirit, or of the renewed nature, which we are to do, are named. And as the apostle had chiefly named works of the flesh, not only hurtful to men themselves, but tending to make them so to one another, so here he chiefly notices the fruits of the Spirit, which tend to make Christians agreeable one to another, as well as to make them happy. The fruits of the Spirit plainly show, that such are led by the Spirit. By describing the works of the flesh and fruits of the Spirit, we are told what to avoid and oppose, and what we are to cherish and cultivate; and this is the sincere care and endeavour of all real Christians. Sin does not now reign in their mortal bodies, so that they obey it, Romans 6:12, for they seek to destroy it. Christ never will own those who yield themselves up to be the servants of sin. And it is not enough that we cease to do evil, but we must learn to do well. Our conversation will always be answerable to the principle which guides and governs us, Romans 8:5. We must set ourselves in earnest to mortify the deeds of the body, and to walk in newness of life. Not being desirous of vain-glory, or unduly wishing for the esteem and applause of men, not provoking or envying one another, but seeking to bring forth more abundantly those good fruits, which are, through Jesus Christ, to the praise and glory of God.

This I say then--Repeating in other words, and explaining the sentiment in Galatians 5:13, What I mean is this."
Walk in the Spirit--Greek, "By (the rule of) the (Holy) Spirit." Compare Galatians 5:16-18, Galatians 5:22, Galatians 5:25; Galatians 6:1-8, with Romans 7:22; Romans 8:11. The best way to keep tares out of a bushel is to fill it with wheat.
the flesh--the natural man, out of which flow the evils specified (Galatians 5:19-21). The spirit and the flesh mutually exclude one another. It is promised, not that we should have no evil lusts, but that we should "not fulfil" them. If the spirit that is in us can be at ease under sin, it is not a spirit that comes from the Holy Spirit. The gentle dove trembles at the sight even of a hawk's feather.

Walk in the Spirit. Under its guidance, as it directs. We have its directions in the words of Christ and the apostles. He who is guided by the Spirit will not obey the lusts of the flesh.
The flesh lusteth against the Spirit, etc. The desires of the flesh and the Spirit are in conflict. They war within us. One would lead in one direction, and the other in another.
So that ye cannot. The Greek is not so strong as this. It implies that the two wills within us hinder us from doing as we would by their conflict.
But if ye be led by the Spirit. If the desire of the Spirit prevails. Those "led of the Spirit are the sons of God" (Romans 8:14), and are free from the law. The law with its carnal ordinances in Paul's view was adapted to a fleshly condition.

I say then - He now explains what he proposed, Galatians 5:13. Walk by the Spirit - Follow his guidance in all things. And fulfil not - In anything. The desire of the flesh - Of corrupt nature.