It's been said that the most difficult point in all the study of divinity is understanding the covenant that God made with Israel at Sinai. Is it a legal covenant? Or is it a gracious covenant? Is it a Covenant of Works, or is it a Covenant of Grace? It's difficult to deny that Sinai belongs to the Covenant of Grace. But for those who accept it as such, there are difficult questions to grapple with. One of the most difficult questions is this: If the Mosaic Covenant truly belongs to the Covenant of Grace, how do you explain that the requirement of the Law was perfect obedience? Here's why this question is so difficult: What God requires in the Covenant of Grace is faith; and actually, faith alone. That's God's requirement in the Covenant of Grace. But though some try to deny it, it's obvious from a clear reading of passages such as Galatians 3:10-12 and Romans 10:5 (cf. Deuteronomy 27:26 and Leviticus 18:5) that at Mt. Sinai, God was indeed requiring perfect obedience of Israel. Faith and perfect obedience are two mutually exclusive systems. So, how do you reconcile the tension? How can you defend the fact that Sinai was indeed part of the Covenant of Grace (requiring faith), if it's clear that God required perfect obedience under Moses? Most people don't know it, but the Puritans wrote extensively about this issue in particular. Along with others, Francis Turretin wrote on this subject in his Institutes of Elenctic Theology (1685).
Turretin deals with the question at hand in at least three places. The first section is found under the heading, “The Twofold Economy of the Covenant of Grace” (V2, pp216-232). Here Turretin tells us:
“And hence we can clearly gather what is to be determined about a question here agitated by some—whether the decalogue promulgated on Mount Sinai contained nothing except the Covenant of Grace and its pure stipulation [or not]. For since from what has already been said, it is evident that the manner of this lawgiving was terrific, smiting with fear their consciences and by the severity of its threatenings removing them from the sight of God, everyone sees that this was not the manner or the genius of the Covenant of Grace (which exhibits God to us as appeased and recalls sinners to itself by the sweetness of its promises). Besides, the law (contained in the decalogue) is of natural right, founded on the justice of God; while the Covenant of Grace is of positive and free right, founded on his good pleasure and mercy. The latter sets forth a surety, promises remission of sins and salvation in his satisfaction; not only demands but also effects obedience. But in the decalogue, no mention either of a surety or promise of salvation to be given to sinners occurs; but a bare promise of life to those doing and a threatening of death to transgressors. Hence the law of works (comprised in the decalogue) is everywhere contradistinguished by Paul from the law of faith and the promise of grace (Romans 3:27; Galatians 3:17-18) for as the law is not of faith (Galatians 3:12), so neither is faith of the law. So great is the contrariety [IE, opposition] between these two means that they are wholly incompatible with each other.” (p226).
“This we do not say, as if we wished either to deny that the Covenant of Grace had then been made with the Israelites (which is expressly taught in Deuteronomy 5:2 and is easily inferred, both from its sanction given in Exodus 19:5 and from its solemn confirmation and ratification alluded to in Exodus 24:8-9 where mention is made of the sprinkling of the blood of victims and the approach of the elders to God). Or as if we supposed the decalogue had nothing in common with the Covenant of Grace and was nothing else than the Covenant of Works itself, renewed for the purpose of recalling the people to it, that they might seek life from it. For since the law was made weak in the flesh after sin (Romans 8:3), the way to life by it became altogether impossible for man. Hence Paul testifies that the law was not given that it might give life (Galatians 3:21) or that the promise first given might be abrogated (Galatians 3:17), but 'on account of transgressions,' that sin being uncovered by it, the necessity of grace might be the more clearly seen.” (p226). Turretin then continues in the following paragraph: “Thus it is rightly said that the decalogue belonged to the Covenant of Grace; yea, in a measure flowed from it inasmuch as it was promulgated from the counsel of God that it might serve him—both antecedently as a schoolmaster, by convincing of sin, bringing to it men smitten with fear of death and despairing of themselves; and consequently as a rule, prescribing the measure of obedience and holiness demanded by God in the Covenant of Grace. Thus God willed that there should be in the decalogue various connections with the Covenant of Grace to recall the people to it, in order that from a knowledge of their own weakness and the terrible denunciation of death, they might not wholly despair of the grace of God. Even the preface (in which he professes himself to be the God of his people, who led them out of Egyptian bondage) and the promises annexed to the second and fifth precept, teach this with sufficient clearness.” (pp226-227).
Again: “Meanwhile it pleased God to administer the Covenant of Grace in this period under a rigid legal economy—both on account of the condition of the people still in infancy and on account of the putting off of the advent of Christ and the satisfaction to be rendered by him. A twofold relation ought always to obtain [IE, be considered]: the one legal, more severe, through which by a new promulgation of the law and of the Covenant of Works, with an intolerable yoke of ceremonies, he wished to set forth what men owed and what was to be expected by them on account of duty unperformed. In this respect, the law is called the letter that kills (2 Corinthians 3:6) and the handwriting which was contrary to us (Colossians 2:14), because by it men professed themselves guilty and children of death, the declaration being written by their own blood in circumcision and by the blood of victims. The other relation was evangelical, sweeter, inasmuch as 'the law was a schoolmaster unto Christ' (Galatians 3:24) and contained 'the shadow of things to come' (Hebrews 10:1), whose body and express image is in Christ. Hence, as much of trouble and vexation as that economy brought in its former relation, so much of consolation and of joy it conferred in the latter upon pious men attending to it and seeking under that bark and veil the spiritual and evangelical truth (which the Holy Spirit taught them by a clearer revelation). God supplied more and greater helps according to the time, not only by promises and oracles often repeated, but also by more expressive types and more perfect shadows and figures, in which they had a more exact delineation of the thing itself and a more accurate picture of Christ crucified before their eyes as it were in types.” (p227).
Turretin then continues and concludes: “According to that twofold relation, the administration can be viewed either as to the external economy of legal teaching or as to the internal truth of the gospel promise lying under it. . .eternal life [was set forth] according to the clause, 'Do this and live.' On the part of the people, it was a stipulation of obedience to the whole law or righteousness both perfect (Deuteronomy 27:26; Galatians 3:10) and personal and justification by it (Romans 2:13). But this stipulation in the Israelite covenant was only accidental, since it was added only in order that man by its weakness might be led to reject his own righteousness and to embrace another's, latent [IE, hidden] under the law.” (p227).
So far, Turretin has told us a few things. First, there is a massive difference between the Law and the gospel, so that we can say not only that the Law is not of faith—but that faith is not of the Law. Indeed, these two systems are mutually exclusive, for one proclaims life and justification upon the condition of obedience, while the other proclaims life and justification upon the condition of faith. But secondly, despite what Turretin had just said—he denies that the Law was given as a renewed republication of the Covenant of Works—but that it rather belongs wholly and unreservedly to the Covenant of Grace. How so? In that it's demands served both to cause men to flee to the Covenant of Grace on the one hand, but no less to instruct those who belonged to Christ on the other. Thus, Turretin here distinguishes a two-fold function of the Law, arguing that we must understand the Law both as legal and evangelical. This is nothing less than the common Puritan distinction of the Law as both largely and strictly understood (though Turretin does not use those words here). In particular, the Law does indeed tell us: “Do this and live”, but it does so intentionally in order to drive us to Christ that in Him we might believe and live.
The second section in Turretin that deals with our question is his next chapter in Volume 2, falling under the heading: “The Difference between the Old and the New Covenants” (pp233-239). Here, Turretin begins to apply the terms “broadly” and “strictly” taken—not just to the Law—but to the entire Old Testament (or old covenant) as a whole. Broadly taken, the old covenant contained “the doctrine of grace delivered to the ancients, promising salvation and life. . .under the condition of repentance and faith in the Messiah about to come” (pp233-234). “Strictly, however, it denotes the Covenant of Works or the moral law given by Moses—the unbearable burden of legal ceremonies being added, absolutely and apart from the promise of grace. The former [IE, the broader sense] was signified properly and of itself (if the scope and intention of the lawgiver be considered). . .not to abolish the promises, but to lead unto Christ. The latter [IE, the stricter sense] is accessory and accidental, springing from an ignoring of the true end and the devising of a false. The true end was Christ for righteousness to every believer (Romans 10:4), but the self-righteous Jews did not obtain this end. . .Hence they invented a false end, maintaining that the law was given in order that by its observance they might be justified before God and be saved (Romans 10:3-5). Against this error the apostle everywhere disputes from that hypothesis which takes the law strictly and opposes it to the promise. . .However, we readily grant that the Old Testament and the Mosaic Covenant taken strictly and absolutely as to the legal relation differ in entire substance from the New. Hence the law and Moses are opposed to grace and to Christ (John 1:17) and by Paul the letter and the Spirit, the ministration of condemnation and of righteousness (2 Corinthians 3:6-7). . . [But] taken broadly and with the other evangelical relation (clothed, namely, with its pedagogical circumstances), it did not differ as to substance, but only as to manner of dispensation.” (pp234-235).
Turretin continues: “It is one thing for the old covenant strictly taken to differ essentially from the new. The apostle had this in mind in the allegory of Sarah and Hagar (Galatians 4:24), the former generating to freedom, the latter to bondage. He disputes against the false apostles who confounded the law and the gospel, which is referred to also in 2 Corinthians 3:6-7, in the antithesis between 'the letter' and 'the Spirit,' 'the ministration of condemnation' and 'of righteousness.' It is however another thing (when broadly considered as to economy) to be opposed as to substance, which we deny.” (p236). And again: “The opposition of the law and the gospel (in as far as they are taken properly and strictly for the Covenant of Works and Grace and are considered in their absolute being) is contrary. They are opposed as the letter killing and the Spirit quickening; as Hagar gendering to bondage and Sarah gendering to freedom, although the law more broadly taken and in its relative being is subordinated to the gospel. But the opposition of the Old and New Testaments broadly viewed is relative, inasmuch as the Old contained the shadows of things to come (Hebrews 10:1) and the New the very image.” (pp236-37).
Again, let's try to summarize this second section from Turretin. Here he begins to flesh out the historic Puritan distinction between the law largely (or broadly) taken and strictly taken. The difference is that he is speaking actually of the old covenant instead of the Law—but his thoughts are one and the same. Broadly taken, the old covenant (or law) holds out Christ to us to be embraced by faith; but strictly taken, it demands of us nothing short of perfect obedience. Turretin clarifies for us that the reason we can take Sinai as belonging to the Covenant of Grace is that the Law (or old covenant) largely taken speaks to us of Christ. Though it is true, that the Law (or old covenant) strictly taken is a way indeed completely contrary to the gospel, still, because this strict sense is subordinated to the larger, broader sense in which the Law (or old covenant) is given, we can (and must) think of the whole as belonging wholly to the Covenant of Grace. The mistake of the Jews was not adding to the Law the stricter sense (for it was inherent in the Law), but rather taking away from the Law the broader sense—for Christ was indeed the end of the Law.
The third section in Turretin is found under the heading, “The Limbus of the Fathers,” and is in the context of objecting to the view that the Mosaic Covenant was a Subservient covenant. Turretin first explains this view (pp262-263) then argues against it (pp263-267). He afterwards seeks to further clarify exactly how it is that he understands the substance and essence of the Mosaic Covenant. In his words:
“The Mosaic Covenant may be viewed in two aspects: either according to the intention and design of God and in order to Christ; or separately and abstracted from him. In the latter way, it is really distinct from the Covenant of Grace because it coincides with the Covenant of Works and in this sense is called the letter that killeth and the ministration of condemnation when its nature is spoken of (2 Corinthians 3:6-7). But it is unwarrantably abstracted here because it must always be considered with the intention of God, which was, not that man might have life from the law or as a sinner might be simply condemned, but that from a sense of his own misery and weakness he might fly for refuge to Christ.” (p267). Again: “The law is said 'to be not of faith' (Galatians 3:12), not as taken broadly and denoting the Mosaic economy, but strictly as taken for the moral law abstractly and apart from the promises of grace (as the legalists regarded it who sought life from it).” And a page later, Turretin writes: “The specific difference of a covenant cannot make a diversity of condition, expressed by the law and gospel—of the former imperfect obedience; of the latter in faith. It was not required in the same way, nor for the same end. For faith in Christ is demanded primarily and intended chiefly, but perfect obedience (under punishment of death and the curse) only subordinately and relatively to faith and the righteousness of faith. By convincing man of his sin and weakness, it forced him to seek a remedy in Christ by faith (as we have already said).” (p268). And Turretin concludes: “It is one thing to speak of the law in itself (which had the form of a Covenant of Works and was enacted not with the end of making alive, but to convict of transgression, extort the confession of debt and lead to Christ); another concerning the Sinaitic covenant itself, in which the law was enacted. In the former sense, the law is called a handwriting against us and the minister of condemnation (2 Corinthians 3:9; Colossians 2:14); but in the latter sense, that covenant had the lively oracles (Acts 7:38) and contained the saving promises of the grace of Christ.” (p269).
This is a reaffirming of what Turretin had told us in the last section. What he continues to emphasize in this section here is the reason why it was that God saw fit to give the Law in the more strict sense. And he tells us that the intention of God in giving the Law in the stricter sense (“Do this and live”) was never for us to try to actually earn our salvation by keeping the Law—but rather to show us just how sinful we are, and in order to drive us to Christ, as freely offered in the gospel contained in the Law as largely taken.
We'll finish with one last paragraph from Turretin (contained in the same section). It is wonderfully rich, and reminiscent also of how Francis Roberts ends his thoughts on the Mosaic Covenant (though Turretin does so in a way that is much more condensed). He says: “Again, these two conditions are proposed because they are necessary to the salvation of the sinner: perfect obedience in Christ to fulfill the righteousness of the law. . .without which the justice of God did not permit life to be given to us; faith however in us that the perfect obedience and satisfaction of Christ might be applied to us and become ours by imputation. Thus what was demanded of us in the Covenant of Works is fulfilled by Christ in the Covenant of Grace. Nor is it absurd that in this way justification takes place by works and by faith—by the works of Christ and by our faith. And thus in sweet harmony the law and the gospel meet together in this covenant. The law is not administered without the gospel, nor the gospel without the law. So that it is as it were a legal-gospel and an evangelical-law; a gospel full of obedience and a law full of faith. So the gospel does not destroy the law, but establishes it (Romans 3:31) by giving us Christ, who perfectly fulfilled it. And the law is not against the gospel, since it refers and leads us to it as its end.” (p268).