Avoiding the Extremes of Antinomianism and Legalism

The law as a rule of life steers a middle course between antinomianism and legalism. Neither antinomianism nor legalism are true to the law or the gospel. Antinomianism stresses freedom from the law's condemnation at the expense of the believer's pursuit of holiness. It accents justification at the expense of sanctification.... [A]ntinomianism fails to see that abrogation of the law's condemning power does not abrogate the law's commanding power.

By contrast, legalism so stresses the believer's pursuit of holiness that obedience to the law becomes something other than the fruit of faith. Obedience becomes a constitutive element of justification. The commanding power of the law for sanctification suffocates the condemning power of the law for justification.

Legalism denies in practice, if not in theory, the Reformed concept of justification. The Reformed concept of the law as a rule of life helps the believer safeguard, both in doctrine and in practice, a healthy balance between justification and sanctification. Justification leads to and finds its proper fruit in sanctification. Salvation is by grace alone and cannot help but produce works of grateful obedience. - Joel R. Beeke, "Publisher's Introduction," in John Colquhoun, A Treatise on the Law and the Gospel (Soli Deo Gloria Publications, 2009), pages xxii-xxiii).