XV. In Scripture, we find two covenants of God with man: the Covenant of Works, otherwise called, the Covenant of Nature, or the Legal and the Covenant of Grace. The apostle teacheth us this distinction, Rom. 3:27, where he mentions the law of works, and the law of faith by the law of works, understanding that doctrine which points out the way in which, by means of works, salvation is obtained; and by the law of faith, that doctrine which directs by faith to obtain salvation. The form of the covenant of works is, “The man that doth these things shall live by them,” Rom. 10:5. That of the covenant of grace is, “Whosoever believeth in him shall not be ashamed,” Rom. 10:11. These covenants of mercy agree,
- 1st. That, in both, the contracting parties are the same, God and man.
- 2dly. In both, the same promise of eternal life, consisting in the immediate fruition of God.
- 3dly. The condition of both is the same, viz., perfect obedience to the law. Nor would it have been worthy of God to admit man to a blessed communication with him, but in the way of unspotted holiness.
- 4thly. In both, the same end, the glory of the most unspotted goodness of God.
But in these following particulars they differ:
- 1st. The character or relation of God and man, in the covenant of works, is different from what it is in the covenant of grace. In the former, God treats as the Supreme Lawgiver, and the Chief Good, rejoicing to make his innocent creature a partaker of his happiness. In the latter, as infinitely merciful, adjudging life to the elect sinner consistently with his wisdom and justice.
- 2dly. In the covenant of works there was no mediator. In that of grace, there is the mediator, Christ Jesus.
- 3dly. In the covenant of works, the condition of perfect obedience was required to be performed by man himself, who had consented to it. In that of grace, the same condition is proposed, as to be, or as already performed, by a mediator. And in this substitution of the person consists the principal and essential difference of the covenants.
- 4thly. In the covenant of works, man is considered as working, and the reward to be given as of debt; and therefore, man’s glorying is not excluded, but he may glory, as a faithful servant may do, upon the right discharge of his duty, and may claim the reward promised to his working. In the covenant of grace, man, in himself ungodly, is considered in the covenant as believing; and eternal life is considered as the merit of the mediator, and as given to man out of free grace, which excludes all boasting, besides the glorying of the believing sinner in God, as his merciful Saviour.
- 5thly. In the covenant of works, something is required of man, as a condition which, performed, entitles him to the reward. The covenant of grace, with respect to us, consists of the absolute promises of God, in which the mediator, the life to be obtained by him, the faith by which we may be made partakers of him, the benefits purchased by him, and the perseverance in that faith, in a word, the whole of salvation, and all the requisites to it, are absolutely promised.
- 6thly. The special end of the covenant of works was, the manifestation of the holiness, goodness, and justice of God, conspicuous in the most perfect law, most liberal promise, and in that recompense of reward, to be given to those who seek him with their whole heart. The special end of the covenant of grace is, “the praise of the glory of his grace,” Eph. 1:6, and the revelation of his unsearchable and manifold wisdom: which divine perfections shine forth with lustre in the gift of a mediator, by whom the sinner is admitted to complete salvation, without any dishonour to the holiness, justice, and truth of God. There is also a demonstration of the all-sufficiency of God, by which not only man, but even a sinner, which is more surprising, may be restored to union and communion with God.
—Herman Witsius, The Economy of the Covenants Between God and Man: Comprehending a Complete Body of Divinity, trans. William Crookshank, vol. 1 (London: T. Tegg & Son, 1837), 26–27.