Genesis 15:8 And he said, Lord God, whereby shall I know that I shall inherit it?
The Lord just reiterated His Covenant Promise by reaffirming who He is, what He did, and what He will do: ”I am the Lord. I brought you out of Ur of the Chaldees (Babylon, the World, the cursed life), I will give you this land to inherit (the kingdom of God, eternal life).” Abram’s response was once again typical of all humans: “How will I know?” He wanted a sign, a confirmation, some tangible evidence.
Even though Abram believed the Lord, he still asked for a visible sign to reinforce his already God-given faith. God responded. He was gracious to give a sign. He would make a unilateral covenant with Abram. ”Covenant cutting” was done by cutting animals in half and laying the pieces side by side. Then the two parties would walk together between animal halves, and thus each would bind himself to keep the terms of the covenant. This was a graphic way of shaking hands or signing a document. Thus each one was bound to keep his promise to the other.
However, in this case only one party passed through the pieces, and that was the Lord Himself only. The Lord was the smoking pot and the flaming torch. Abram did not pass through; he only watched. This was a unilateral covenant, an unconditional promise binding God to keep His Word, with no conditions placed upon mankind. Faith is the recipient of the guarantee. We do not make a promise; we watch.
God granted Abram’s request for a sign by graphically making this one-way covenant. That was “how he could know.” God keeps His promise to us at the cross and the empty tomb. He is gracious and kind to ”cut a covenant” with us in Baptism and Holy Communion. ”This is the blood of the new covenant shed for you.” We watch and we receive. This is how we can know that we will inherit the kingdom.