The apostle is still carrying on the same design as in the Gal. 4:12-16, 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, Gal. 4:18; 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!