Down the Bloody Alleyway By Himself
There were different kinds of covenants in the ancient world ... Sometimes one of the signs of this covenant agreement and corresponding threat was to take animals, tear them apart, and put them side by side with a kind of bloody alleyway between the two parts, and then the two parties of the covenant would walk between the divided animals so as to signify "May this be done to me if I break this covenant. May I be torn apart. May I be cut in half."
So Abraham prepares the animals. Obviously, however, God is not a human being to walk beside Abraham between animals. Abraham falls into a deep sleep, and in his sleep he sees a firepot, something to represent the presence of God. What is so stunning is that instead of the firepot moving between the animals side by side with Abraham (so that the two of them are saying, in effect, “May it be done to us if either of us breaks the covenant”), God goes down this bloody alleyway all by himself. He takes the full responsibility for the fulfilment of the covenant all by himself. That is grace.
- D. A. Carson, The God Who is There, 51-52