| Barnes' Notes on the Bible But it is good to be, zealously affected - The meaning of this is, "Understand me: I do not speak against zeal. I have not a word to say in its disparagement. In itself, it is good; and their zeal would be good if it were in a good cause." Probably, they relied much on their zeal; perhaps they maintained, as errorists and deceivers are very apt to do, that zeal was sufficient evidence of the goodness of their cause, and that persons who are so very zealous could not possibly be bad men. How often is this plea set up by the friends of errorists and deceivers! And not only when I am present with you - It seems to me that there is great adroitness and great delicacy of irony in this remark; and that the apostle intends to remind them as gently as possible, that it would have been as well for them to have shown their zeal in a good cause when he was absent, as well as when he was with them. The sense may be, "You were exceedingly zealous in a good cause when I was with you. You loved the truth; you loved me. Since I left you, and as soon almost as I was out of your sight, your zeal died away, and your ardent love for me was transferred to others. Allow me to remind you, that it would be well to be zealous of good when I am away, as well as when I am with you. There is not much true affection in that which dies away as soon as a man's back is turned." The doctrine is, that true zeal or love will live alike when the object is near and when it is removed; when our friends are present with us, and when they leave us; when their eye is upon us, and when it is turned away.
Clarke's Commentary on the BibleIt is good to be zealously affected - It is well to have a determined mind and an ardent heart in reference to things which are laudable and good. Not only when I am present - You were thus attached to me when I was among you, but now ye have lost both your reverence and affection for me. Your false teachers pretended great concern for you, that you might put all your confidence in them; they have gained their end; they have estranged you from me, and got you to renounce the Gospel, and have brought you again into your former bondage.
Gill's Exposition of the Entire BibleBut it is good to be zealously affected,.... A zealous affection when right is very commendable, as the instances of Phinehas, Elijah, John the Baptist, and our Lord Jesus Christ show, and a contrary spirit is very disagreeable. But then it must be expressed in a good thing; in a good cause, for God, and the things of Christ; for the Gospel, and the ordinances of it, and for the discipline of God's house, and against immorality and profaneness, errors and heresies: and it should be "always"; not at certain times, and upon some particular accounts, but it should be constant, and always continue; it should be ever the same towards God, Christ, and his ministers: and not only when I am present with you; by which the apostle suggests, that while he was with them they were zealously attached to him and truth; but no sooner was he gone from them, but their zealous affection abated, and was fixed on others, which discovered their weakness, fickleness, and inconstancy; whereas he was always the same to them, and bore the same love to them, as the following words show.
Vincent's Word StudiesIt is good - in a good thing Ζηλοῦσθαι to be zealously sought, in the same sense as before. It is passive. It is good for you Galatians to be zealously sought. In a good thing (ἐν καλῷ) answers to οὐ καλῶς not honorably, Galatians 4:17. In a good matter - the interest of the gospel. Thus Paul would say: "These Judaisers zealously strive to win you over to their views; but they do not do this in an honorable way. There is no harm in seeking to interest and enlist you, provided it is in a good cause."
Geneva Study BibleBut it is good to be {s} zealously affected always in a good thing, and not only when I am present with you. (s) He sets his own true and good love, which he earnestly held for them, against the wicked vicious love of the false apostles.
People's New Testament 4:18 It is good to be zealously sought affected always in a good thing. To exhibit zeal and feeling is a good thing. It was good to show this feeling when he was present with them. But now it was changed in respect of himself. It was only when he was present.
Wesley's Notes 4:18 In a good thing - In what is really worthy our zeal. True zeal is only fervent love.
Jamieson-Fausset-Brown Bible Commentary18. good to be zealously affected-rather, to correspond to "zealously court" in Ga 4:18, "to be zealously courted." I do not find fault with them for zealously courting you, nor with you for being zealously courted: provided it be "in a good cause" (translate so), "it is a good thing" (1Co 9:20-23). My reason for saying the "not well" (Ga 4:17; the Greek is the same as that for "good," and "in a good cause," in Ga 4:28), is that their zealous courting of you is not in a good cause. The older interpreters, however, support English Version (compare Ga 1:14). always-Translate and arrange the words thus, "At all times, and not only when I am present with you." I do not desire that I exclusively should have the privilege of zealously courting you. Others may do so in my absence with my full approval, if only it be in a good cause, and if Christ be faithfully preached (Php 1:15-18).
Matthew Henry's Concise Commentary4:12-18 The apostle desires that they would be of one mind with him respecting the law of Moses, as well as united with him in love. In reproving others, we should take care to convince them that our reproofs are from sincere regard to the honour of God and religion and their welfare. The apostle reminds the Galatians of the difficulty under which he laboured when he first came among them. But he notices, that he was a welcome messenger to them. Yet how very uncertain are the favour and respect of men! Let us labour to be accepted of God. You once thought yourselves happy in receiving the gospel; have you now reason to think otherwise? Christians must not forbear speaking the truth, for fear of offending others. The false teachers who drew the Galatians from the truth of the gospel were designing men. They pretended affection, but they were not sincere and upright. An excellent rule is given. It is good to be zealous always in a good thing; not for a time only, or now and then, but always. Happy would it be for the church of Christ, if this zeal was better maintained.
Matthew Henry's Whole Bible CommentaryVerses 17-18 The apostle is still carrying on the same design as in the foregoing verse, which was, to convince the Galatians of their sin and folly in departing from the truth of the gospel: having just before been expostulating with them about the change of their behaviour towards him who endeavoured to establish them in it, he here gives them the character of those false teachers who made it their business to draw them away from it, which if they would attend to, they might soon see how little reason they had to hearken to them: whatever opinion they might have of them, he tells them they were designing men, who were aiming to set up themselves, and who, under their specious pretences, were more consulting their own interest than theirs: "They zealously affect you," says he; "they show a mighty respect for you, and pretend a great deal of affection to you, but not well; they do it not with any good design, they are not sincere and upright in it, for they would exclude you, that you might affect them. That which they are chiefly aiming at is to engage your affections to them; and, in order to this, they are doing all they can to draw off your affections from me and from the truth, that so they may engross you to themselves." This, he assures them, was their design, and therefore they must needs be very unwise in hearkening to them. Note, 1. There may appear to be a great deal of zeal where yet there is but little truth and sincerity. 2. It is the usual way of seducers to insinuate themselves into people's affections, and by that means to draw them into their opinions. 3. Whatever pretences such may make, they have usually more regard to their own interest than that of others, and will not stick at ruining the reputation of others, if by that means they can raise their own. On this occasion the apostle gives us that excellent rule which we have, v. 18, It is good to be zealously affected always in a good thing. What our translation renders in a good man, and so consider the apostle as pointing to himself; this sense, they think, is favoured both by the preceding context and also by the words immediately following, and not only when I am present with you, which may be as if he had said, "Time was when you were zealously affected towards me; you once took me for a good man, and have now no reason to think otherwise of me; surely then it would become you to show the same regard to me, now that I am absent from you, which you did when I was present with you." But, if we adhere to our own translation, the apostle here furnishes us with a very good rule to direct and regulate us in the exercise of our zeal: there are two things which to this purpose he more especially recommends to us:-(1.) That it be exercised only upon that which is good; for zeal is then only good when it is in a good thing: those who are zealously affected to that which is evil will thereby only to do so much the more hurt. And, (2.) That herein it be constant and steady: it is good to be zealous always in a good thing; not for a time only, or now and then, like the heat of an ague-fit, but, like the natural heat of the body, constant. Happy would it be for the church of Christ if this rule were better observed among Christians! | 
