Text in red are my additions.
Gal 5:1 Stand fast and be not held again under the yoke of bondage.
Recalls the Sarah-Hagar allegory of Gal 4:21-31. It also prepares for the warning found in 5:13.
Gal 5:13 For you, brethren, have been called unto liberty. Only make not liberty an occasion to the flesh: but by charity of the spirit serve one another.
You have been called unto liberty, freedom from the ceremonial precepts of the Jewish law, freedom also from the temporal penalties which under that law formed the sanction of the moral precepts, but not freedom from the obligation of those moral precepts themselves, which are of nature, pre-existent to the law given on Sina (Rom 2:14-15), and were confirmed by Christ (Matt 19:17). Only, these moral precepts which in the Old Law were enforced by threats of temporal punishment, are in the New Law facilitated by grace. This is St. Paul s witness against Antinomianism (lawlessness), for which also read Rom 6.
By charity serve one another, δουλευετε, meaning: be in bondage to one another. The bondage of charity to replace the bondage of fear and of the law. The Greek word δουλευετε (douleuete) is derived from douleuo, to be a slave.
Gal 5:14 For all the law is fulfilled in one word: Thou shalt love thy neighbour as thyself.
Expanded into three verses, Rom 8:8-10. The quotation is from Leviticus 18:19, where for friend the Septuagint has neighbour. The Jewish doctors were prone to limit the extension of this term neighbour to Jews, a limitation which Our Saviour sets aside in the parable of the Good Samaritan (Luke 10:29-37).
“Since the perfection of charity involves two precepts, the love of God and the love of our neighbour, why does the Apostle make mention only of the love of our neighbour? Why but because men can lie concerning the love of God, seeing that temptation comes less frequently to try it, but in the matter of the love of their neighbour they are more easily convicted of not possessing it, when they deal unjustly with men? Besides, who can love his neighbour, that is, every man, unless he love God, by whose precept and gift he is enabled to compass the love of his neighbour? Since then such is the nature of either precept that the one cannot be kept without the other, it is generally sufficient to mention merely one of them, when there is question of the works of justice: but that one is more aptly mentioned, on which a transgressor is more easily convicted” (St. Augustine). Cf. 1 John 4:20.
Gal 5:15 But if you bite and devour one another: take heed you be not consumed one of another.
If you bite and devour one another. It is St. Jerome’s remark, that the Apostle has described each province by its own special features; and that the same vestiges of errors or virtues as he described were to be met with in the same places three centuries afterwards. Galatia attained to unhappy notoriety as a nest of wrangling heresies, particularly of outrageous forms of Montanism and Manichaeism.
Gal 5:16 I say then: Walk in the spirit: and you shall not fulfill the lusts of the flesh.
The spirit–the flesh. “By the flesh he means the inclination of the mind to the worse: by the spirit, the indwelling grace” (Theodoret). So St. Chrysostom explains the flesh to be “the earthy view of things.” The flesh in fact is the whole man, both in his intellectual and in his animal faculties, but in his animal faculties particularly, inasmuch as he feels an inclination to break away from God and set up his rest in the goods of this life.
The Apostle says of it: There dwelleth not in my flesh that which is good (Rom 7:18); and again, the wisdom of the flesh is not subject to the law of God, neither can it be (Rom 8:7). The flesh endures in every man, even in a saint on earth, till his dying day. Only in Our Saviour and in His Blessed Mother there was flesh, but not technically the flesh. In the day of the resurrection, the flesh, as here spoken of, shall be no more.
Still the theological maxim, quoted by the Council of Trent (sess. 5, can. 5) holds good, that “in the regenerate (by baptism) there is nothing that God hates.” The flesh is not wicked, though it prompts to wickedness: it is not sin, nor sinful, though it tempts us to sin. As St. Chrysostom says: “Though the passions give trouble, their ravings go for nothing,” in the man who walks by the spirit, that is, leads. a super natural life of faith, hope, and charity. That is why St. Paul writes here, not you shall not feel, but you shall not fulfil, that is, carry out into human act, the lusts of the flesh.
In all that has been written, be it clearly understood that by the flesh is not meant the body, a point which St. Chrysostorn elaborates with great care.
Gal 5:17 For the flesh lusteth against the spirit: and the spirit against the flesh: For these are contrary one to another: so that you do not the things that you would.
So that ( ινα, equivalent to ωστε according to a later Greek usage, expressing not purpose but result, cf. 1 Thess 5:4) you do not the things that you would. That is : So that either way you do not all your inclination: for if you follow the spirit, you do not the inclination of the flesh ; and if you follow the flesh, you deny the prompting of the spirit: you have thus some manner of self-renunciation either way. Cf. Rom 6:16.
Gal 5:18 But if you are led by the spirit, you are not under the law.
Not under the law that threatens slaves, but under the spirit that leads the children of God. Cf. Rom 6:14; Rom 8:2.