Contrary to what some Dispensational writers have claimed, the Christian church, in the post-apostolic period, has always taught covenant theology. The Epistle of Barnabas (c. AD 120) wrote a fairly mature covenantal explanation of the history of redemption, the unity of the covenant [of grace], and the centrality of Christ in the history of salvation. The same was true of Justin Martyr (c. AD 150) and Irenaeus (c. AD 170). By the late patristic period, it was fairly settled that God had entered into a covenant with Adam before the fall. Through the Middle Ages, these things were not often deeply explored as much as assumed, although there were some unhappy developments in covenant theology.
The Reformation brought with it a renewed attention to the covenant. Martin Luther brought an evangelical (in the sixteenth-century sense of the word) Protestant approach to the covenant (of grace) in his lectures in Genesis in the 1530s. Before that, however, in Zürich, in the early 1520s, Huldrych Zwingli was appealing to the unity of the covenant (of grace) against the Anabaptists as was Johannes Oecolampadius in Basel. Calvin made extensive use of the covenant of grace in his explanation of the Christian faith for most of thirty years.
By the early 1560s, it was clear that the Reformed were reading the Scriptures covenantally. Zacharias Ursinus and Caspar Olevianus both made extensive use of covenant theology in their teaching and writing in the 1560s through the mid-1580s. Both appealed to a covenant of nature before the fall and the covenant of grace after the fall to articulate Luther’s distinction between law and gospel. For all the Reformed churches and theologians, it was a given that there is one covenant of grace with multiple administrations. These are just some of the topics we discussed in the Guilt, Grace, Gratitude podcast. – R. Scott Clark