Horton’s main point is that there are two types of covenants that run concurrently throughout Scripture, one type is that of a suzerainty treaty and the other is a covenant of grant. Into the former category falls the Sinaitic covenant (which in some sense is a republication of the Edenic covenant of works), while the Abrahamic, Davidic, and New covenants fall into the latter category. It is under this rubric that Scripture gives expression to the categories of “law” and “gospel.” In other words, the Reformed, following Scripture and Paul in particular, have always couched their law/gospel language and antithesis in the covenantal language of “do this and live” equaling law, and “it is finished” equaling gospel.

via Covenant and Justification: Horton vs. Piper and Wright.

The two covenants Paul contrasts in Romans and Galatians is a covenant that promises all nations will be blessed in Abraham’s seed and a covenant that establishes Israel as a special nation separate from the rest.

But Horton doesn’t want this contrast. Rather, he wants to prove a contrast between “earning” and “receiving as a gift through faith.” [Note: not denying the contrast but denying that God ever gave an “earning” covenant, or that “earning” issues are the same as the question of conditions]

But, among other problems, his exegetical argument is incoherent.