Also of great interest here is Scott Clark’s collection of quotations from the Reformed orthodox available here. Even if that were all that were available, it would bury the contention that the Law/Gospel distinction is only Lutheran. Most important, of course, are the confessional documents for answering this question (Clark has quite a few of those quoted). I wish I had Dennison already to help me with this (and I also fervently wish the other two volumes were already out!). At least I have still have Schaff.
The Second Helvetic Confession, chapter 12 deals with the law, and plainly affirms the first use of the law (which is that most closely associated with the Law/Gospel distinction), and further distinguishes when it says “We know that the Scripture of the law, if it be expounded by the Gospel, is very profitable to the Church, and that therefore the reading of it is not to be banished out of the Church” (Schaff, p. 856). As has already been noted, the Heidelberg Catechism clearly affirms the Law/Gospel distinction (certainly that is how Ursinus, one of the two authors of the Catechism, understood it).
French Confession, article 23 (Schaff, pp. 372-373): “We believe that the ordinances of the law came to an end at the advent of Jesus Christ; but, although the ceremonies are no more in use, yet their substance and truth remain in the person of him in whom they are fulfilled. And, moreover, we must seek aid from the law and the prophets for the ruling of our lives, as well as for our confirmation in the promises of the gospel.” Then, following this section, in article 25, we see this: “Now as we enjoy Christ only through the gospel…” (p. 374). Very similarly, the Belgic Confession, article 25, which did model itself at least somewhat off the French Confession.
The Marrow of Modern Divinity clearly equates the law with the covenant of works and the gospel with the covenant of grace (see pp. 27ff.). Quoting Musculus, “for it is manifest, says Musculus, that the word which signifies covenant, or bargain, is put for law: so that you see the law of works is as much as to say, the covenant of works.” It should be noted here that the Marrow has an excellent way of understanding the continuity between the covenant of works and the Mosaic covenant. The Ten Commandments are described as the matter of the covenant of works. It cannot properly be called the covenant of works (as it is given in Exodus 20) because it does not have the form of the covenant of works (in terms of the agreement). See pp. 28-29.
Thomas Ridgely’s commentary on the Larger Catechism (p. 303): “Hence arises a clear sight of the need which persons have of Christ, and of the perfection of his obedience. When we find that we are condemned by the law, and that righteousness is not to be attained by our own obedience to it, we are led to see our need of seeking it elsewhere; and when the gospel gives us a discovery of Christ, as ordained by God to procure for us righteousness, or a right to eternal life by his obedience, we see the need we have of faith in him, whereby we derive from him that which could not be attained by our own conformity to the law.”
And John Colquhoun (for these quotations and analysis, I simply copied and pasted from Donald MacLean’s email to me. Donald MacLean’s blog is here):
1) The law is necessary from the nature of God but the gospel is voluntary. (146-7). 2) The law is partly revealed by nature (Rom 2:14-15) but he gospel is only known by revelation from heaven (Matt 11:27). (147). 3) The law comes and demands perfect obedience the gospel comes and shows the grace and mercy of God to sinners. (147-8). 4) The law shows us what we should be but “The gospel teaches us how we may be made such, namely by union and communion with Christ…” (148). 5) The law says, “Do and you shall live; you shall, by performing personal and perfect obedience, entitle yourselves to eternal life…'” but “The gospel says ‘Live, for all is already done; all the righteousness, meritoriousness of eternal life for believers, is already fulfilled by the second Adam…'” (148). He expands on this: “The Law is God in a command, but the Gospel is God in Christ, God in a promise. The law gives man more to do for eternal life than they are able to do; the gospel gives them less to do than they are willing to do. The law gives man all the work: the gospel gives grace all the work and all the glory.â€ (149). 6) The promises of the law are “conditional” but the promises of the gospel (as a covenant) are “absolute”. (150-1). 7) The law “condemns , and cannot justify a sinner” but the gospel “justifies, and cannot condemn the sinner who believes in Jesus.” (150-1). 8) The law “says to every man, ‘You are a sinner’. The gospel says, ‘The blood of Jesus Christ cleanses from all sin.'” (151-2). 9) The law hardens (Rom 4:15) while the gospel softens the heart. (152). 10) The law allows for boasting but the gospel excludes it (Rom 3:27). (152-3). Colquhoun also notes we should not confound law/gospel with old/new testament (153-5). He closes his chapter by applying the truths he has discussed stating, “None can successfully minister true consolation to a discouraged and disconsolate believer without teaching his to distinguish, in his own case, between the law and the gospel.” (157).