The later half of “Wisdom” recounts various episodes in Israel’s redemption history. In chapter 18 the writer(s) is addressing Israel’s exodus from Egypt. It gets down to verses 20-25 and mentions Aaron stepping in and making atonement for Israel when they had sinned in the wilderness. The specific incident referred to is found in Numbers 16.46-50. What I found interesting is how the writer(s) describes Aaron’s act. Here is the text taken from “The Orthodox Study Bible”(OSB):
“….and a plague came upon the multitude in the desert; but the wrath did not last long. For a blameless man hastened and acted as their champion. He carried the instrument of his ministry (“he brought forward the shield of his ministry“ -RSV CE & NRSV): prayer and the atonement (ἐξιλασμὸν-”propitiation“ RSV CE & NRSV) of incense, and withstood the anger and put an end to the calamity, showing that he was Your servant. He conquered the wrath not by strength of body, and not by the power of weapons, but by a word he subdued the punisher, … He stood in the midst (“intervened” RSV CE & NRSV) and drove back the wrath and cut off its path to the living” (Wisdom 18.20b-23).
What is significant is the play between God’s justified wrath and atonement, “propitiation” (RSV CE & NRSV). “Wisdom” uses a word that is closely related to what is found in 1 John 4.10. There John says that “this is love, not that we loved God, but that He loved us and sent His son to be the propitiation for our sins.”
What is pictured in “Wisdom” is how expiation (the covering or removing of our sins) and Christus Victor (Christ victoriously delivering us from our corruption/bondage) goes along with the High Priest (Aaron) conciliating the justified anger of God toward Israel. I think this helps us to grasp what is going on in 1st John. God, who is rightly and justly opposed to us because of our sin, has permitted corruption, death and evil to bind us. Yet, because He loves us, He has acted on our behalf. He has sent His own Son, the blameless One, to become our champion. This Son of God, Jesus the Messiah, willingly entered into the midst of the fray, conquered the well-deserved wrath of the Father by His death on the cross (what is commonly known as penal subsitution), emancipating His people from what they justly deserved - corruption, death, evil, and the justice of God. And in this liberation, Christ Jesus destroyed the works of the devil (1 John 3.8b) and made us fit to be adopted into the inter-Trinitarian fellowship of love, joy, and peace; making us by grace what He is by nature - the well-beloved children of God (1 John 3.1-3; 4.13-16)!
If I am reading this correctly, then what we see is that propitiation (conciliating God’s justified wrath deserved by His people) is (1) a legitimate definition behind ἐξιλασμὸν and related words; (2) is tied to expiation and Christus victor; (3) and in the context of 1st John, is also linked to moral example (this is real love, now that you have experienced this love, go and do likewise).
Truly the love of God for His people was rich, deep, and robust!