The word translated “propitiation” in the KJV Romans 3:25 is hilasterion in Greek, Some of the root words behind or inside it have meanings like drawing up a fish, carrying what one has lifted, choosing; mercy, grace, favor. The KJV translates it in Hebrews as “mercy seat.”
In Exodus 25, God tells Moses that the mercy seat above the ark of the covenant is where “I will meet with you and commune with you.” It is the covering on which the priest sprinkled blood from the sin offerings on the day of atonement when also the scapegoat was sent into the wilderness (Lev. 16). It was such a holy place that entering it without preparation, for instance clouds of incense, could be fatal. Thus it was in the most interior of the rooms of the Temple. But at the death of Jesus, it was exposed by the tearing of the veil in the Temple, and as the author of Hebrews tells us, Jesus entered both as High Priest and sacrifice, fulfilling God’s will, which has always been to make a way for us to turn and run toward God rather than away. Hilasterion even shares a root with the word “hilarity." God extends good cheer toward us and it gives God pleasure to do so.
“Propitiation” comes from the Latin, and a related word is propitious, which means favorable. The Latin roots are pro-for and petere-to seek. “To seek for” would be a literal translation of the Latin roots behind “propitiate.” So it is possible to see Jesus our propitiation meaning Jesus as God seeking for us. Again. Jesus reveals God, Jesus embodies God. Jesus does only what he sees his Father doing. “My Father never rests from doing good, and neither do I,” Jesus says.
Knowing that God is on exactly the same page as Jesus with regard to seeking and saving all of us who are lost brings great joy, and is good news for everyone. And then we can enjoy the sheer happiness hidden behind the word propitiation. When the angels sang, “Glory to God, peace on earth, good to each human being.”
From Romans 3, paraphrased:
We have proved before that both Jews and Gentiles are all under sin. As it is written, there is none righteous, no, not one; there is none that understands, there is none that seeketh God…deceitful, bitter, violent, destructive, causing misery, knowing nothing of peace, no reverence for God. …
And right at this moment the justice, the rightness of God
which the law and the prophets witnessed to
is being exposed and recognized apart from the law.
And the justice of God
by means of the faithfulness of Jesus Christ
comes to all and upon all that are believing, for there is no distinction.
All have sinned, each and every one misses the path and wanders from God’s law, arriving too late to earn God’s good opinion;
all are being made just what they ought to be
as a gift from God’s grace and good will
by means of the liberation paid for by Christ Jesus.
God has shown Christ Jesus to us as a sign of mercy, favor, and joy,
his good faith sealed in his own blood;
God bears with all of us to demonstrate God’s own justice and integrity in passing over and disregarding our past sin, our wandering from God’s law.
God has shown this evidence right now at the opportune time that God is just as God should be,
both the just one, the one who is right,
and the one who makes all of us just as we ought to be,
we who are placing our confidence in Jesus.