After Adam and Eve fall into sin, God speaks first to the serpent, promising enmity between the serpent’s seed and the woman’s seed, and declaring that her offspring will crush the serpent’s head even as his heel is struck. Theologians have long called this verse the protoevangelium — the first gospel — because it is the earliest promise in Scripture of a coming deliverer who would undo the serpent’s work.
The sermon then traces that promised ‘war between two seeds’ through the rest of the Old Testament: Satan’s repeated attempts to corrupt or destroy the godly line, from the conflict of Cain and Abel, to a false heir schemed against Abraham, to Esau’s hostility toward Jacob, and persecution the true seed faces again and again. Each attempt fails, and the line of promise runs unbroken from Adam’s fall to its fulfillment in the crucifixion of Jesus Christ.