Which is not another
It is no Gospel, no joyful sound, no good news, and glad tidings; the doctrine which attributes justification to the works of the law, or mixes grace and works in the business of salvation, which was the doctrine of these false teachers, is no Gospel; not truly so, however it may be called; nor does it bring any solid peace and joy to distressed minds. There is but one pure Gospel of the grace of God, and Christ, and his apostles; there is not one and another; there is but one faith, one doctrine and scheme of faith; the Gospel is single and uniform, all of a piece, has no yea and nay, or contradiction in it; this trumpet gives no uncertain sound, nor any dreadful, but a joyful one:
but there be some that trouble you;
meaning the false apostles, whose names he does not think fit to mention, as being unworthy to be named, and to have their names transmitted to posterity. These troubled the churches with their doctrines and principles, by raising disputes and controversies among them, injecting doubts and scruples into their minds, which puzzled and confounded them, and made them uneasy, and which broke in upon that peace of soul which the Gospel brings and establishes; for no true solid peace is attained to, and enjoyed, but by the doctrine of justification by the righteousness of Christ, pardon by his blood, and atonement by his sacrifice, which the doctrine of justification by works tends to destroy.
And would pervert the Gospel of Christ;
which has Christ for its author, subject, and preacher; and particularly the doctrine of justification by his righteousness, which they sought to change, to throw into a different shape and form, to adulterate by mixing it with the works of the law, and so, if possible, destroy it: to this they showed a good will, but were not able to effect, for the Gospel is an everlasting one; it is immovable, and so is that particular doctrine of it; it remains, and will remain in spite of opposition to it. Thus the apostle prudently lays the blame of the Galatians removing from the Gospel to another upon the false teachers, hoping he should be able to reclaim them by solid arguments, and gentle methods.