Just some thoughts on the Covenant of Grace and Law.
(1) If there are multiple diverse covenants in the Bible then there is an overarching covenant of Grace to unite all the diverse covenants.
(2) There are multiple diverse covenants in the Bible
(3) Therefore, there is an overarching covenant of Grace to unite all the diverse covenants.
Why affirm (1), when it is not obvious nor more plausibly true than its denial? Explanatory power and scope? Why not merely affirm one divine plan to unite the diverse covenants?
I've noticed some make a category mistake on the nature of the Mosaic Law. First, they assert the law is a whole composed of parts. The OT indicates the whole Mosaic Law is a simple indivisible unit thus without parts; but nevertheless, we may make artificial obligatory distinctions. Second, they confuse epistemic divisions with ontic divisions. Third, they implicitly deny any given law legislated by God is moral in nature.
Hebrews 7:12 elucidates a change of law:
(1) If there is a change in priesthood then there is a change in law.
(2)There is a change in priesthood.
(3) Therefore there is a change in law
James 2:10 shows us the simplicity and indivisibility of the Mosaic Law with its 613 commandments.
If any given person violates part of the Law then she violates the whole Law.
Moreover, If we assume (*1) the Mosaic Law Covenant is an agreement between God and Israel. Whereby God was to be Israel's King under a theocracy. God legislated 613 commandments that was to be Israel's rule of law including those people that were subject to the protection/jurisdiction of the nation of Israel.
If we grant (*1) then (1) to (3) follows:
(1) If the Mosaic Law is abolished then the Mosaic Law is not objectively binding.
(2) The Mosaic Law is abolished.
(3) Therefore the Mosaic Law is not objectively binding.
One can object to premise (2) but must then affirm the Mosaic Law, in some sense, which is patently false.
We grant that there are different punishments proportionate to violations of God's commands as legislated by God under a theocracy. But this does not logically demonstrate any given command is not moral in nature; nor does it establish any given command is ontologically ceremonial.