If the Ten Commandments and the other aspects of the Torah could only and always be truly kept by sinful people evangelically rather than legalistically, i.e. from the heart, as our Lord reminded us in e.g. the Sermon on the Mount, how does this impact upon the Republication of the Covenant of Works theory?

Could you clarify your question some?

The moral law as summarised in the Ten Commandments is at least implicitly a demand for a change of heart on the part of those within the Covenant People who are characterised as "the wicked" rather than "the righteous" e.g. in the Psalms, as it is impossible for a sinner to do true good before God unless one is justified by God and one's heart is changed by God.

This was the case under the Old Covenant as much as under the New.

Obviously this didn't apply to Adam who didn't need evangelical, or other, conversion but preservation, perseverance and continuation in obedience.

This thought was partly stimulated by our last interaction on the PB, Casey, so there's probably little originality in it.

The moral law as taught under Moses is at least implicitly evangelical, as the ceremonial law as taught under Moses is explicitly evangelical.

I think Jesus and the Apostles made it pretty clear that the Pharisees/Jews had misunderstood the purpose of the law and so misused it (i.e., as a means for one's justification). Dispensationalism sides with the Pharisees' interpretation of the OT, the law, etc.; God's plan just didn't work so He provided a new plan. Republicationism at least gives some credibility to the Pharisee's view of the purpose of the law and, IMHO, echo's dispensationalism's error. It's a short jump from "God gave us the law so that, by our (partial) obedience, we might keep the land and be blessed" (a valid interpretation, according to Republicationism) to "God gave me the law so that, by my (partial) obedience, I might reach to eternal blessedness" (obviously something Republicationists don't want us to conclude from the giving of the law).

I wanted some more background to your question, so I went to a website
with a contributor that I know well.

I found this statement rather concerning:

...The law of Moses was, in the first place, a re-enactment of the covenant of works [but that is not its only function]. A covenant is simply a promise suspended upon a condition. The covenant of works, therefore, is nothing more than the promise of life suspended on the condition of perfect obedience.

It's a terribly weak view of covenant (Hebrew, berith). I prefer G. Vos'

... the outstanding characteristic of a berith is its unalterableness, its certainty, its eternal validity ... The berith as such is a 'faithful berith' something not subject to abrogation. It can be broken by man and the breach is a most serious sin, but this again is not because it is the breaking of an agreement in general; the seriousness results from the violation o f the sacred ceremony by which its sanction was effected.

He's also careful to say that we cannot identify the Covenant of Works with the Old Testament which he defines as belonging after the fall and stands as the first of two divisions of the covenant of grace.

I don't see how Moses can be seen as a re-enacting the covenant of works. Just about every reformed standard that I know of makes a distinction between The Covenant of Works and the Covenant of Redemption. Moses has his place in the unfolding of the Covenant of Redemption, showing the perfect standard reflecting God's holy character that had to be fulfilled in the perfect life of the lamb who was to come.

Originally Posted by Richard Tallach

The moral law as taught under Moses is at least implicitly evangelical, as the ceremonial law as taught under Moses is explicitly evangelical.

It being explicitly evangelical is obvious, IMHO, on account of the Prologue. Also, consider what David VanDrunen said in his inaugural lecture, "The Two Kingdoms and the Ordo Salutis: Life beyond judgment and the question of a dual ethic" (WTJ Vol. 70, No. 2: Fall 2008), p. 220: "Clearly, love in some sense is a requirement of the natural law, known apart from justification." The footnote has: "If the moral law and natural law are summarized in the Decalogue and the Decalogue is summarized by the two great love commandments (as commonly taught in Reformed theology and in the Reformed confessional standards), then this statement must be true. The love prescribed in the covenant of works and in the natural law is a love apparently to be practiced without considerations of mercy and forgiveness. This is also strikingly true of the Decalogue, whose precepts make no mention of mercy or forgiveness either." (The bold sentence is what I want to highlight, I included the rest for some context.) I can't quite make out why he says this; does he mean the law doesn't suggest we should show mercy or forgive our neighbor? Anyway, how can he claim that "the Decalogue['s] ... precepts make no mention of mercy"? The Decalogue does explicitly make mention of mercy: "shewing mercy unto thousands of them that love me, and keep my commandments." If the Decalogue is the covenant of works republished, how can there be a mention of grace to those who love God in the Decalogue itself? The mention of mercy in the Decalogue only makes sense if the Decalogue was given in the context of the covenant of grace.