In his book, The Westminster Assembly, Robert Letham makes an assertion on page 233 that many today may assume to be correct,...
both the Confession and the Larger Catechism say that law and gospel are different means of administering the one covenant of grace...And on page 234 he writes:
WCF 7.5 spells out clearly that the law was an administration of the covenant of grace.One may assert that position, but the WCF and WLC do not state that conclusion:
WCF 7.5. This covenant was differently administered in the time of the law, and in the time of the gospel: under the law, it was administered by promises, prophecies, sacrifices, circumcision, the paschal lamb, and other types and ordinances delivered to the people of the Jews, all foresignifying Christ to come; which were, for that time, sufficient and efficacious, through the operation of the Spirit, to instruct and build up the elect in faith in the promised Messiah, by whom they had full remission of sins, and eternal salvation; and is called the old testament.
WLC Q. 34. How was the covenant of grace administered under the Old Testament?
A. The covenant of grace was administered under the Old Testament, by promises, prophecies, sacrifices, circumcision, the passover, and other types and ordinances, which did all foresignify Christ then to come, and were for that time sufficient to build up the elect in faith in the promised messiah, by whom they then had full remission of sin, and eternal salvation.The Westminster Divines did not teach that the law was a means of administering the covenant of grace. Chad Van Dixhoorn writes in his book, Confessing The Faith:
... we are reminded that the covenant of grace was 'administered' differently 'in the time of the law, and in the time of the gospel'. The one time is symbolized by the law engraved on stones... p 103Yet!...
The redeeming feature of this time of the law was that these types and ordinances all pointed directly to a coming Christ... p 104Nowhere in the Westminster Standards does it state that the covenant of grace in the Old Testament was administered by the law or by the commandments. This is not to say that the law commandments weren't and aren't essential to the outworking of the covenant of grace in God's work of bringing sinners to Christ and sanctifying the elect. Yet properly, the law itself speaks only of our duty before God and its condemnation of sinners for the breach of it. As its primary use (WLC 95, 96, 97) the law, through the work of the Holy Spirit, shines a light on our corruptions and lack of conformity to it. The law points sinners to Christ. Sinners, both unregenerate and regenerate, convicted by the law through the agency of the Holy Spirit are driven to see their need of the Savior and further, in the lives of the redeemed, increases both their gratitude to Christ and their desire to conform to its commands.
WLC Q. 97. What special use is there of the moral law to the regenerate?
A. Although they that are regenerate, and believe in Christ, be delivered from the moral law as a covenant of works, so as thereby they are neither justified nor condemned; yet besides the general uses thereof common to them with all men, it is of special use, to show them how much they are bound to Christ for his fulfilling it, and enduring the curse thereof in their stead, and for their good; and thereby to provoke them to more thankfulness, and to express the same in their greater care to conform themselves thereunto as the rule of their obedience.But in the law no grace or power is offered to sinners for cleansing from or the overcoming of sin. As John Owen wrote,
The law guides, directs, commands, all things that are against the interest and rule of sin. It judgeth and condemneth both the things that promote it [sin] and the persons that do them; it frightens and terrifies the consciences of those who are under its [sin's] dominion. But if you shall say unto it [the law], “What then shall we do? this tyrant, this enemy, is too hard for us. What aid and assistance against it [sin] will you afford unto us? what power will you communicate unto its destruction?” Here the law is utterly silent, or says that nothing of this nature is committed unto it of God: nay, the strength it hath it gives unto sin for the condemnation of the sinner: “The strength of sin is the law.” (A Treatise of the Dominion of Sin and Grace)What then, or Who, will then come to the aid of sinners under this heavy load? John Owen continues...
But the gospel, or the grace of it, is the means and instrument of God for the communication of internal spiritual strength unto believers. By it do they receive supplies of the Spirit or aids of grace for the subduing of sin and the destruction of its dominion…Indeed, WCF 7.6 teaches that in the New Testament we find the covenant of grace fulfillment of not the law but the Old Testament types and shadows...
Under the gospel, when Christ, the substance, was exhibited, the ordinances in which this covenant is dispensed are the preaching of the Word, and the administration of the sacraments of baptism and the Lord's Supper...In this time of the gospel, it is now these three New Testament ordinances by which God administers the covenant of grace to his people. These ordinances are not law, but the verbal and visible proclamations of the grace of God offered to sinners - Christ offered in the gospel -- the fulfillment of the promises, types, and shadows of the Messiah found under the law and in the time of the law. Christ was 'the substance' of the covenant of grace then promised but now revealed in the time of the gospel. God's means of administering the covenant of grace, under or in the law with the Old Testament types and shadows, did not change in the New Testament, but rather found its fulfillment in Christ under the gospel.
Q. 35. How is the covenant of grace administered under the New Testament?
A. Under the New Testament, when Christ the substance was exhibited, the same covenant of grace was and still is to be administered in the preaching of the word, and the administration of the sacraments of baptism and the Lord's supper; in which grace and salvation are held forth in more fullness, evidence, and efficacy, to all nations.