Through the redemption that is in Christ Jesus, whom God set forth as a propitiation by his blood.
Romans 3:24.25.
Alongside justification and redemption we now have the thought of propitiation (or: atonement). Propitiation means that God has been fully satisfied concerning His holy demands regarding sin. For Jesus Christ suffered death for sinners. He gave His blood, the means of propitiation, to atone for their sins.
The early Christians were acquainted with this word as the designation of the mercy seat of the ark of the covenant. The ark contained the tablets with the ten commandments and stood in the innermost room of the Jewish sanctuary. The ark had a golden lid with two golden cherubim. These were special angels who guarded God’s holiness, served Him and carried out judgment. The ark of the covenant might well instil terror in some; yet it was the centre of Jewish worship. However, none other than the high priest was allowed to enter the inner sanctuary, the holy of holies, and then only once a year.
The particular purpose was that the high priest should sprinkle the blood of animal sacrifices on the mercy seat once every year. God had so ordered it. And only if that happened could God dwell in the midst of His people Israel. The blood settled the matter of guilt, as it were, and made atonement. The blood stood between the cherubim and the law in the ark. Hence the term “mercy seat”. The judgment throne in the inner sanctuary, God’s dwelling place, became a “throne of grace” (cf. Hebrews 4:16).
Image: By Illustrator of Henry Davenport Northrop’s ‘Treasures of the Bible’, 1894 – http://www.lavistachurchofchrist.org/Pictures/Treasures%20of%20the%20Bible%20(Moses)/target15.html, Public Domain, https://commons.wikimedia.org/w/index.php?curid=9425677