The Old Testament contains 39 books that are categorized as books of the Law, history, poetry, wisdom, and prophetical books.
Despite its diverse contents, it is much more than a simple anthology. It is tied together by a successive string of five major covenants that God made with His people.
A covenant is a binding agreement between two or more parties. When we speak of Biblical covenants, we are referring to instances where God has entered into an agreement with mankind that involves both promises and responsibilities for each party.
While there are many covenants and promises found in the Old Testament, a study of the following will provide you with a framework to better understand redemptive history. (Note that this is not meant to be a discussion on Covenant Theology, but instead a look at the Old Testament through the lens of these particular covenants.)
Five of the primary covenants in the Old Testament are the Noahic, Abrahamic, Mosaic, Davidic, and the New Covenant. Each of these covenants is reflective of two of the main categories of covenants known in the Ancient Near East:
Suzerian-Vassal: This term harkens back to a time when a king would make a promise to his subjects, or a treaty between kings would be that depended on obedience to specific terms. You can think of this covenant as a conditional promise.
Royal Grant: Unlike the Suzerian-Vassal agreements, a Royal Grant requires no action on the part of the beneficiary. It is an unconditional promise given from one party to another.