Stephen G. Myers’s God to Us: Covenant Theology in Scripture comes recommended as an excellent introductory resource to covenant theology.
As expected of a RHB publication, the book opens with spiritual warmth and doctrinal precision. Myers begins by observing that we come to know God better when we understand our covenant relationship with him.
He then turns to the matter of what covenant theology is by surveying the biblical covenant terminology. Myers concludes from the terminology that covenants are both contractual and relational.
Myers then defines covenant theology as “the study of God’s eternal, unchanging purpose to bring a people to Himself through covenantal relationship” (9). This definition may be too broad since this definition would encompass progressive covenantalists and dispensationalists. However, Myers then specifies the three covenants commonly held by covenant theologian: the covenant of redemption, the covenant of works, and the covenant of grace. Even here the description of covenant theology is broad because, if the new covenant is equated with the covenant of grace, progressive covenantalists and certain dispensationalists would affirm all these covenants. Myers goes on to specify that the covenant of grace is made up of the covenants with Noah, Abraham, Israel at Sinai, David, and the new covenant. Myers identifies these covenants as different administrations of the covenant of grace. At this point covenant theology is distinguished from progressive covenantalism and all forms of dispensationalism. However, certain covenantal Baptists would reject this composite covenant of grace, preferring to equate the covenant of grace with the new covenant. Myers notes that there is some variety within covenant theology that he will discuss later.
In my opinion, the overlap between the views is because these systems are all developed by orthodox Christians who are seeking to make sense of the biblical data. Some systems, however, do a better job than others of accounting for all the data.