The counterpart to (English) Antinomianism, which I considered last time, is Neonomianism. People today typically use the term “Neonomian” to depict views that they consider to be legalistic or moralistic. Historically, however, it was coined and employed by English Congregationalists at the end of the 17th century to label the perceived Arminian views of the moderate English Presbyterians.
The Congregationalist Isaac Chauncy was the first one to use the term. Shortly after Tobias Crisp’s sermons were reprinted, the Presbyterian Daniel Williams published a book excoriating Crisp for his antinomianism. His book was really a thinly veiled critique of many Congregationalists. Chauncy was more than a little offended, and wrote voluminously against Williams and charged him with what he called Neonomianism. Over against the charge of Antinomianism, the retort of “Neonomianism” is, one must say, a stroke of linguistic and rhetorical genius. Certainly, it is better than the riposte of Arminianism, which Robert Traill had done in a published letter.
What did Chauncy mean by his term “Neonomianism”? Essentially, Chauncy believed that Williams taught that Christ’s death satisfied the old law, namely the Covenant of Works, and procured a new law of repentance, faith and sincere obedience. By keeping the new law, the sinner becomes inherently righteous, which in turn becomes the ground for his justification. The sinner therefore is not justified by Christ’s righteousness but by his own righteousness. Christ’s righteousness, or rather the effects of his righteousness, must be received in order to avoid being judged by the old law and be eligible to be saved by the new law. But the righteousness of Christ does not play a direct role in justification. The sinner’s own righteousness, according to the new law, comes to the fore in justification as a sinner is pardoned on the grounds of his faith and repentance. In short, when the sinner believes, the effects of Christ’s righteousness—not Christ’s righteousness itself—are imputed to him to free him from the Covenant of Works (legal righteousness), he becomes truly righteous on the basis of the new law (gospel righteousness), and so is justified. Such a scheme, argued Chauncy, is intrinsically meritorious. Moreover, it is both antinomian and neonomian or legalistic. There is first the “Abrogation of the Old Law,” which is the epitome of antinomianism; and secondly, there is the “Erection of a new Law of Works for our justification, which is Neonomianism.”
This “Neonomian” role of faith in justification is akin to the Arminian view. The problem, however, was that moderate Presbyterians like Williams weren’t Arminians, or Neonomians, as defined by Chauncy. This is not to say that they didn’t have their own unique formulation of justification and related doctrines. The issue was that their formulations were easily misunderstood and confused with Arminianism/Neonomianism, especially by people who were seated across the aisle. Although they unequivocally rejected the term, the name has stuck as a label for their views, at least in the academic world. David P. Field has identified the following as Neonomians to one degree or another: John Howe, William Bates, Daniel Williams, Richard Baxter, Joseph Alleine, and Matthew Henry. Consequently, it is necessary, as it is with Antinomianism, to distinguish between types of Neonomianism.  
If you are interested in learning more about Neonomianism from a historical standpoint, then you may want to consider reading the article I co-authored in this forthcoming volume, A New Divinity: Transatlantic Reformed Evangelical Debates during the Long Eighteenth Century.
Patrick Ramsey