The Mercy Seat (or mercyseat)
On top of the ark was a lid called the mercy seat on which rested the cloud or visible symbol of the divine presence. Here God was supposed to be seated, and from this place He was supposed to dispense mercy to man when the blood of the atonement was sprinkled there.
In a manner of speaking, the mercy seat concealed the people of God from the ever-condemning judgment of the Law. Each year on the Day of Atonement, the high priest entered the Holy of Holies and sprinkled the blood of animals sacrificed for the atonement of the sins of God’s people. This blood was sprinkled on the mercy seat. The point conveyed by this imagery is that it is only through the offering of blood that the condemnation of the Law could be taken away and violations of God’s laws covered.
The Greek word for “mercy seat” in Hebrews 9:5 is hilasterion, which means “that which makes expiation” or “propitiation.” It carries the idea of the removal of sin. In Ezekiel 43:13-15, the brazen altar of sacrifice is also called hilasterion (the propitiatory or mercy seat) in the Septuagint (the Greek translation of the Old Testament) because of its association with the shedding of blood for sin.
What is the significance of this? In the New Testament, Christ Himself is designated as our “propitiation.” Paul explains this in his letter to the Romans: “Being justified freely by His grace through the redemption that is in Christ Jesus, whom God set forth as a propitiation by His blood, through faith, to demonstrate His righteousness, because in His forbearance God had passed over the sins that were previously committed” (Romans 3:24-25 NKJV).