Whenever there is a revival of biblical theology, there will be a rediscovery of the significance of the covenantal structure of God’s redemptive activity from Noah through Moses to the new covenant in Christ. In this context, questions about the role of the law of God in the life of the new-covenant people invariably arise. When Paul realized that every covenant pointed to, and was fulfilled in, Christ, he found himself faced with the question, “Why, then, the law?” (Galatians 3.19). Throughout his ministry, he regularly encountered two wrong answers. One led to legalism by smuggling law into gospel. The other led to antinomianism with its implication that the gospel abolished law altogether.
This pattern of things resurfaced at the time of the Reformation and, in the following century, the Puritan period. By the 1630s and 1640s, the role of the law was being hotly debated in both old and New England. The Westminster divines gave as close attention to their chapter Of the Law of God as to any section of the Confession of Faith.
Thus, it was in the context of rumors and fears of both legalism and antinomianism that The Marrow of Modern Divinity first saw the light of day in 1645.
“Isms” (such as legalism and antinomianism) can be dangerous, not only for those who espouse them but also for those who employ the categories. They too easily become “one size fits all” pigeon-holes. Individuals are not categories, and treating them as such can be quite misleading and often ignores their context.
In particular, we need to be cautious in using language in a pejorative way. Words ending in –ism and –ist seem to lend themselves to emotive rather than descriptive use. In the era of the Marrow itself, “legalist” was a convenient put-down for a Puritan. Think, here, of Shakespeare’s caricature in his portrayal of the legalistic killjoy Malvolio (Latin malum + voleo = “I will ill”!). On the other hand, in eighteenth-century Scotland, it was the Marrow brethren who feared “legalism” and were, in turn, suspected of incipient antinomianism by those who were fearful that the Marrow promoted it, for the General Assembly’s condemnatory act had listed a whole series of its expressions deemed to be antinomian in nature.
From: The Whole Christ: Legalism, Antinomianism, and Gospel Assurance – Why the Marrow Controversy Still Matters by Sinclair B. Ferguson (Wheaton: Crossway, 2016), pp. 75-77.