“Excerpt from “A Treatise on the law and the Gospel” pages 167-168 by John Colquhoun
The law and the gospel the law, likewise, as a rule of life to believers agrees with the gospel. When the law, as a covenant presses a man forward, or shuts him up to the faith of the gospel; the gospel urges and draws him back to the law as a rule (Leviticus 11:44). The law is his schoolmaster to teach him his need of the grace of the gospel; and this grace will have his heart and his life regulated by no rule but the law (2 Peter 1:15–16). Nothing is gospel-obedience but obedience to the law in the hand of Christ as a rule of duty. The gospel is no sooner believed than obedience is yielded, both to the law as a covenant and to the law as a rule. The righteousness of Christ in the hand of faith is obedience to it in the former view, and personal holiness of heart and life to it in the latter. If the law commands believers, the grace of the gospel teaches them to love, and to practice universal holiness (Titus 2:11–12). What the law as a rule of life binds them to perform, the grace of the gospel constraints and enables them to do (Leviticus 20:8; 2 Corinthians 5:14–15). That which the precept of the law requires as a duty, the promise of the gospel affords and effects as a privilege (Ezekiel 18:31 and 36:26–27). Whatever holds the place of duty in the law occupies the place of privilege in the gospel. Duties required in the law are graces or exercises of grace in the language of the gospel. The commands of the law reprove believers for going wrong, and the promises of the gospel, so far as they are embraced, secure their walking in the right way space (Jeremiah 32:40). The former show them the extreme folly of backsliding; the latter are means of healing their backslidings and restoring their souls (Psalm 23:3). The gospel, or word of Christ, dwells richly and none but in such as have the law of Christ put into their minds and written on their hearts. The law cannot be inscribed on the heart without the gospel, nor the gospel without the law. As they are found together in the same divine revelation, so they dwell together harmoniously in the same believing soul. So great is the harmony between them that they can reside nowhere separate from each other. While the precepts of the law show the redeemed how very grateful and thankful they should be for redeeming grace, the grace of Christ in the gospel produces and excites that adorning gratitude. The law enjoins and excites believers to receive daily by faith more and more of the grace of the gospel to qualify them for more spiritual and lively obedience to its precepts; and the gospel supplies them with every motive, preparative, assistance, and encouragement requisite for such obedience.
2 Corinthians 5:13-21