An objection is often raised as to how God could enter into a covenant of works with fallen sinners. (Note: “a” covenant of works, not “the” covenant of works)
It is argued that a covenant that operates upon a principle of works (If you do this, then you will get this) must start from the basis of innocence. If someone is innocent, then they can earn a reward. However, if they are not innocent, if they have a guilt that must be paid, then they cannot earn anything until that guilt is paid. So a fallen sinner cannot enter into a covenant of works for any kind of reward (even temporal) until that guilt is paid (which they cannot do).
It is a strong argument on the face of it. However, the problem is that Scripture throws us a curve ball. Leviticus 18:5 says that the Mosaic Covenant, which is made with fallen sinners, operates upon the principle of “if you do this, then you will get this.” That principle is repeated throughout the Old Testament, particularly in Ezekiel when Israel is being prosecuted for their violation of the covenant. Bryan D. Estelle notes
Leviticus 18:5’s influence on Ezekiel is of paramount importance. The purpose of these echoic allusions in Ezekiel is to show that what Israel has failed to do, God will do… Leviticus 18 allusions are seen throughout the entire book of Ezekiel and not merely restricted (as often) to chapter 20 of Ezekiel where three citations of Lev 18:5 have frequently been noted… Israel’s failure to fulfill the stipulations is highlighted repeatedly in Ezekiel 1-24…
Paul also quotes Leviticus 18:5 twice in the NT. Both times he does so to demonstrate the antithesis between the law and faith (Rom 10:5, Gal 3:12).
Those who object that God could not make a covenant of works with fallen man usually argue that Lev 18:5 is not stating the terms of the Mosaic Covenant. They claim it is just a reference, or proclamation of the original Adamic Covenant and it is just reminding Israelites of it. It’s not stating the terms of the Mosaic Covenant, they argue, only declaring the original terms of the Adamic Covenant. However, not only is this an impossible reading of the text itself, it fails the systematic test as well. (See Guy Waters on Leviticus 18:5)
So, biblically speaking, Lev 18:5 proves that a covenant made with fallen sinners operates upon a works principle. So there must be a problem with the original objection. The problem is that not only are fallen sinners unable to earn anything, fallen sinners are unable to breathe the very air they breathe each day and eat the food they eat each day. They deserve only God’s wrath and death. Yet somehow they continue to eat and breathe and live. That is because of God’s long-suffering towards them. All mankind deserved immediate eternal punishment upon Adam’s breach of his covenant of works. But God delayed and preserved mankind. God is willing and able, while maintaining his justice, to give them gifts (Matt. 5:45) when they only deserve wrath – and to do so apart from union with Christ.
So then what is preventing him from choosing some of those fallen sinners and offering them gifts above and beyond the norm (rain and sun) upon the condition that they do something? There can be no objection of injustice anymore than there can be an objection of injustice on God’s part towards every fallen sinner.
“But,” they will object, “that would mean that there is some kind of grace involved, and therefore it cannot be a covenant of works!” Not so fast. WCF/LBCF 7.1 teach that even the original Covenant of Works was established through God’s “voluntary condescension.” Mankind owed obedience to God by nature without the expectation of any reward, yet God “graciously” condescended to reward that obedience with something. So offering man something that he does not deserve, on the condition of his obedience, is not inconsistent with a covenant of works. Note what Owen says:
The covenant of works had its promises, but they were all remunerative, respecting an antecedent obedience in us; (so were all those which were peculiar unto the covenant of Sinai). They were, indeed, also of grace, in that the reward did infinitely exceed the merit of our obedience; but yet they all supposed it, and the subject of them was formally reward only.
(Hebrews 8:6 commentary)
Finally, here is how John Erskine answers:
But, if this reasoning proves anything, will it not prove, that a God of spotless purity, can enter into a friendly treaty with men, whom yet, on account of their sins, he utterly abhors. And what if it does? Perhaps, the assertion, however shocking at first view, may, on a narrower scrutiny, be found innocent. We assert not any inward eternal friendship between God and the unconverted Jews. We only assert an external temporal covenant, which, though it secured their outward prosperity, gave them no claim to God’s special favour. Where then is the alleged absurdity? Will you say it is unworthy of God to maintain external communion with sinners, or to impart to them any blessings? What then would become of the bulk of mankind? Nay, what would become of the patience and longsuffering of God? Or is it absurd, that God should reward actions that flow from bad motives when we have an undoubted instance of his doing this in the case pf Jehu? Or is it absurd, that God would entail favours on bad men, in the way of promise or covenant? Have you forgot God’s promise to Jehu, that his children of the fourth generation should sit on the throne of Israel? Or have you forgot, what concerns you more, God’s covenant with mankind in general, no more to destroy the earth by a flood (2 Kings 10:30; Gen 9:12)?
Thus there is no valid systematic objection to God making “a” covenant of works with fallen sinners concerning temporal life and blessing in the land of Canaan.
[Note: there is a valid objection God making “the” covenant of works with fallen sinners concerning eternal life. See Republication, the Mosaic Covenant, and Eternal Life.]