As one moves from Dispensationalism to a Reformed understanding of the Scriptures, one must undergo a paradigm shift. I have compared this to the Copernican revolution, going from a geo-centric view of the universe to a helio-centric view.
Both systems have the same data; they both claim to be basing their theology on the exegesis of the Scriptures. However, there are underlying presuppositions that govern the conclusions that one comes to.
One of the key presuppositions on both sides is that of continuity or discontinuity between the Old and New Testaments. Dispensationalists presume discontinuity; whereas Reformed Theologians presume continuity.
For example, when it comes to the relationship between Israel and the Church, Dispensationalists presume discontinuity. The argument goes like this: “The Bible never says that the church is Israel; therefore they are different entities with different purposes and different destinies.”
The Reformed Theologian says, “The Bible never says that the church is not Israel, therefore they are the same.”
The Bible neither explicitly affirms or denies that the church is Israel. The difference is that each side assumes contrary positions.
When the Dispensationalist encounters Scriptures that seem to favor continuity, he falls back upon the lack of a plain statement from Scriptures. Therefore, we should presume discontinuity.
When the Reformed Theologian encounters Scriptures that seem to favor discontinuity, he falls back upon the lack of a plain statement from Scriptures. Therefore, we should presume continuity.
The question we must ask is: which presupposition is most consistent with the Scriptures.?
I started out by presuming discontinuity. As I studied the Scriptures, I kept running up against verses that seemed to teach continuity (e.g., Genesis 12, 15, 17; Galatians 3, 4; Ephesians 2-3; Hebrews 8-10). At first, I was able to explain these away, but I would only encounter more continuity verses. It seemed that continuity was jumping out at me from every page of Scripture.
Finally, I had this radical thought: what if I presumed continuity? I tried this out and found it to be a much more satisfactory explanation of the Scriptures. At every turn, I found that continuity fit much more solidly with the Scriptures. I felt like Copernicus when he found that presuming helio-centrism matched the evidence much more closely than geo-centrism.