The world is attempting to redefine Marriage and a relationship with God in accord with ever-shifting cultural views. In sharp contrast, God has had a specific plan for these two relationships in place from the beginning. Both are termed Covenant Relationships. There is little current teaching in the Christian community about the structure, function, and purposes—or even the definition—of these relationships. Volume One of this three book series begins in by introducing the defining characteristic of Covenant relationships, drawn from the scholarly research of H. Clay Trumbull (The Blood Covenant, 1885)—the exchange and merger of identities and natures. This underlying reality is termed a “one-flesh” relationship in Marriage, and is described as a “new birth” producing a “new creation” in a New Covenant relationship with God. The implications of this underlying reality define the opportunities inherent in these relationships, as well as the duties, obligations, and responsibilities we must fulfill to properly build these relationships. God’s detailed and specific plan, which flows logically from the reality of these relationships, produces growing love over a lifetime, as well as the growth and transformation required in individuals to build both relationships to their potential.