Reformed theology, as many have said, is covenant theology, for the concept of covenant has shaped the development of Reformed thinking. We should expect as much because of our doctrine of sola Scriptura, which says that the Bible is the only infallible authority for Christian faith and practice. Therefore, we want to structure all theological understanding according to Scripture. This demands covenant theology, since covenant is an organizing principle in Scripture.

Given the importance of the biblical doctrine of covenant, all Christians should have at least a basic understanding of what the Bible means by the term covenant. In the Old Testament, the Hebrew word we translate as “covenant” is berith, and it was used for centuries by the ancient Israelites. However, after Alexander the Great conquered the Eastern Mediterranean world and brought with him the Greek language, many Jews became more familiar with Greek than with Hebrew. Consequently, a Greek translation of the Hebrew Old Testament was made during the third century B.C. We know this translation as the Septuagint, and it had a tremendous impact on the writers of the Greek New Testament.

One challenge that the Jews who produced the Septuagint faced was the decision about how best to translate the Hebrew term berith or “covenant,” since there wasn’t any Greek word that precisely matched the Hebrew term. Eventually, the word chosen by the Septuagint translators was the Greek word diathēkē, and this was adopted by the New Testament writers, who, for the most part used diathēkē for the concept of “covenant.”

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