I am currently reading How People Change by Timothy S. Lane and Paul David Tripp. In chapter 4, "Change Is a Community Project," the authors make some interesting comments on Genesis 15:7-21:
What is going on in this strange encounter? Abram is struggling to believe God, so God helps him. He tells him to cut some animals in half. That night, a smoking firepot and a blazing torch pass between the animal halves. God was saying, “If I do not keep my promise to you, may what happened to these animals happen to me! ” This is called a self-maledictory oath. God is saying, “If I don’t keep my end of the bargain, may I be ripped asunder!” Over two thousand years later, God the Son hung on a cross, crying out, “My God! My God! Why have we been ripped asunder?” God allowed what should have happened to us to happen to Jesus. We were the ones who failed, yet the triune God was torn asunder so that we might be united to him and to one another as brothers and sisters in Christ. The perfect love, unity, and joy that existed between the Father, Son, and Spirit were demolished, for a time, for our sake.
This is the ground on which we build all relationships. Every time you are tempted to shun another believer, remember that the Father, Son, and Spirit were torn asunder so that you might be united. When you sin or are sinned against, you are to move toward your sibling in Christ aware that Father, Son, and Spirit were torn asunder so that you might be reconciled! If we approached relationships in the body of Christ with that in view, it would transform our friendships (p. 80).