Ezekiel Hopkins’ The Doctrine of the Two Covenants significantly influenced 17th-century Puritan and Anglican theology by clearly outlining Reformed federal theology, particularly the distinction between the covenant of works and the covenant of grace. It provided a structured explanation of original sin and justified a Protestant understanding of salvation.

Hopkins defined the Covenant of Works (pre-fall, obedience-based) versus the Covenant of Grace (post-fall, faith-based), establishing a rational, and systematic framework for understanding God's relationship with humanity and explained the nature of original sin, defining the inherited corruption and guilt from Adam.

Most significantly, he established a theological reconciliation between Paul (justification by faith alone) and James (justification by works) by arguing that faith justifies the person, while works justify the faith, a position held by puritans in the vein of Richard Baxter, etc.

Hopkins, Ezekiel. The Doctrine of the Two Covenents, wherein in the Nature of Original Sin is at Large Explain'd: St. Paul and St. James Reconcil'd in the Great Article of Justification. With a Discourse of Glorifying God in his Attributes. Now First Published from his Original Manuscripts. London. Printed for Richard Smith at Exeter-Exchange in the Strand. 1712. 472pp.

A good - copy, textually complete and good, front board detached, title and ffep a bit chipped around edges.