John Glas, Testimony of the King of Martyrs Concerning His Kingdom, 1777 
Glas on the Davidic Covenant
Glas on prophetic idiom: "the most part of the prophecies concerning Christ and his kingdom speak almost constantly of the antitype by the types."
Glas' book was written against the sacral (national) model of the church. WLC cites Is. 49:23 are evidence of the civil magistrate's parental authority over his subjects (and his supposed authority to protect the church from false teaching). Note Glas' recognition of typology
He recognized that the promise of the seed of the woman through Jacob is what sustained Israel. Once the promise was narrowed to David, the rest of Israel was cast off.
The Noahic Covenant was "subservient" to the Gen 3:15 promise.
Scottish theologian John Glas on the Old and New Covenants
Glas on OT saints being members of the NC kingdom by means of the promise of Christ.
It is worth noting that John Erskine (1765), John Glas (1777), and Abraham Booth (1788) all sound very, very similar in their description of the Kingdom of Israel vs the Kingdom of Christ. Seems to have been a growing agreement/refinement in the literature.
