What is propitiation? John states that Jesus “is the propitiation for our sins, and not for ours only but also for the sins of the whole world” (1 John 2:2) and, similarly, that the Father “sent his Son to be the propitiation for our sins” (1 John 4:10). The Greek term for propitiation in these instances is hilasmos, and we can understand it better by examining related words in the NT.
Romans 3:25 uses the noun hilastērion―Christ is He “whom God put forward as a propitiation by his blood, to be received by faith. This was to show God’s righteousness, because in his divine forbearance he had passed over former sins.” Hebrews 9:5 uses this noun in identifying the mercy-seat in the Holy Place of Israel’s tabernacle: “Above it were the cherubim of glory overshadowing the mercy seat.”
The verb hilaskomai is instructive as well. Luke 18:13 records the tax collector’s plea, “God be merciful to me, a sinner!” Speaking of Christ, Hebrews 2:17 states “He had to be made like his brothers in every respect, so that he might become a merciful and faithful high priest in the service of God, to make propitiation for the sins of the people.”
Some conclusions from above: (1) propitiation was possible in the OT through the mercy seat (Heb 9:5) but not completely as it would be in Christ (Rom 3:25); (2) Christ Himself is the propitiation (1 John 2:2; 4:10); (3) propitiation is for our sins (1 John 2:2; 4:10), the sins of the people (Heb 2:17), and the sins of the whole world (1 John 2:2); (4) Propitiation was made possible by the blood of Jesus (Rom 3:25); (5) propitiation was made possible by Jesus because He was human (Heb 2:17); (6) propitiation is something Jesus has done in His service to God as our High Priest (Heb 2:17); and (7) propitiation is for those who humbly acknowledge their sin before God (cf. Luke 18:13).
From these conclusions, we can describe propitiation more fully. Being the infinitely holy God that He is, God justly responds to our sins with infinite wrath. Sadly, many experience (and others will come to know) this infinite wrath in hell, a punishment that lasts forever. Others, however, humbly acknowledge their sin before God and place their faith in Jesus who paid the infinite penalty for their sins on their behalf, made possible because Jesus is both God and man. The wrath of God was temporarily satisfied through animal sacrifice in the OT which anticipated the sacrifice of Christ (Heb 9:5; cf. Lev 16), and His wrath is now completely satisfied through Christ’s shed blood (i.e., His death on the cross).
In short, Jesus is the propitiation for our sins, meaning that He is the one who set aside the wrath of God by taking our due penalty for sins upon Himself on the cross. What an amazing Father we have to send His Son to die for us, and what an amazing Son He is to be the propitiation for our sins!