How can we satisfy the demand of the law?
The law's demand is satisfied only through God's mercy, pictured by the mercy seat, because the law is so demanding and all have sinned. No human effort can meet it. Justification is freely by His grace through the redemption that is in Christ Jesus.
Les teaches that the cherubim's wings met over the box of pure beaten gold, indicating a covering of God's mercy. God's mercy is the only thing that could answer to what was in the box, which was the law. The law is so demanding that the only way we can even come close to satisfying its demand is in God's mercy, and that is why there is the mercy seat. Les then points to Romans 3:23-25, where Paul declares that all have sinned and come short of the glory of God, every human from Adam, Jew and Gentile. Yet they are justified freely by His grace through the redemption that is in Christ Jesus, whom God hath set forth.