The Old Covenant and the Law of Moses

Properly speaking the Old Covenant is equivalent to the Mosaic Covenant inaugurated upon Mount Sinai (Jer. 31:31-34; cf. Heb. 8:8-13; Gal. 4:21-31). Like the Creation Covenant, the Old Covenant contains its own specific law—the Mosaic—with its own inherent uses, the primary of which was to reissue to Israel the creation covenant's works principle in order to demonstrate to all men the folly of attempting to secure God's blessings by means of personal observance of the law, and to typologically demonstrate the need to seek an alien righteousness from the hand of the promised Deliverer (Gal. 3:24).

In addition to this pedagogical use, the Mosaic law also governed the civic life of the nation as they existed in the land of Canaan (WCF XIX.4), outlined in great detail the ceremonial means whereby the sins of the people were to be covered until the coming of the Messiah and true High Priest (Heb. 10:1-18; WCF. XIX.3), and demonstrated Yahweh's standards for righteous conduct (Pss. 19:7-10; 119:105).

The nature of the Old Covenant as preparatory and parenthetical demands the conclusion that its law is neither ultimately indispensable nor perpetually binding. The law of Moses was an expression of God's will specifically and covenantally formulated for those to whom it was given. Moreover, part of that covenantal formulation was the law's works principle, which Paul summarizes as "do this and live" and insists is antithetical to the faith principle of the gospel (Gal. 3:12; Rom. 10:5). To attempt extract the kernel of the Decalogue from the husk of its works principle is to put asunder what God hath joined together, for from its bestowal to its removal, the Sinanitic Covenant instilled fear, produced bondage, and perpetuated the nation's juvenility by keeping the kids under the constant, watchful eye of a babysitter.

Here's the point: To insist that all members of the covenant of grace are "under the law" in the same sense (tertius usus legis) is to completely ignore the nature of the law under which God's people in time past labored. The Mosaic law comes with a principle attached that was intended to instill doubt in its subjects (that's the whole point of its "pedagogy").

So aren't you glad it has expired?