The Judaizers in the New Testament taught that, ‘The only way to be justified is sheer hard work. You have to toil at it. The “work” you have to do is the “works of the law”. That is, you must do everything the [moral] law commands and refrain from everything the law forbids.’

It has been the religion of the ordinary man both before and since. It is the religion of the man-in-the-street today. Indeed, it is the fundamental principle of every religious and moral system in the world except New Testament Christianity. It is popular because it is flattering. It tells a man that if he will only pull his socks up a bit higher and try a bit harder, he will succeed in winning his own salvation.

But it is all a fearful delusion. It is the biggest lie of the biggest liar that the world has ever know, the devil, whom Jesus called ‘the father of lies’ (John 8:44).

The two foundation planks of the Christian religion are the grace of God and the death of Christ. The Christian gospel is the gospel of the grace of God. The Christian faith is the faith of Christ crucified. So if anyone insists that justification is by works, and that he can earn his salvation by his own efforts, he is undermining the foundations of the Christian religion. He is nullifying the grace of God (because if salvation is by works, it is not by grace) and he is making Christ’s death superfluous (because if salvation is our own work, then Christ’s work was unnecessary).

Yet there are large numbers of people who, like the Judaizers, are making these very mistakes. They are seeking to commend themselves to God by their own works. They think it noble to try to win their way to God and to heaven. But it is not noble; it is dreadfully ignoble. For, in effect, it is to deny both the nature of God and the mission of Christ. It is to refuse to let God be gracious. It is to tell Christ that he need not have bothered to die. For both the grace of God and the death of Christ become redundant, if we are masters of our own destiny and can save ourselves.

(John Stott, The Message of Galatians, p.61-66)