Summary: The original idea of propitiation came from the pagans.The Christian meaning is much richer as we shall see today. Before we explore what Christian propitiation looks like we have to understand why God needs to be satisfied.
Purpose: To explain why God's wrath must be assuaged before forgiveness is possible.
Aim: I want the listener to glory in what Christ did to absorb God's wrath against our sin.
INTRODUCTION: I won't ask for a raise of hands, but men have any of you ever forgotten your anniversary or your wife's birthday? It's one of the biggest mistakes a husband can make. Forgetting a date important to your wife can make her angry (or at least very annoyed). So, what does a husband often do in a situation like this? He goes out and buys his wife a gift (flowers, jewelry, etc.) hoping that when he gives her the gift she will no longer be mad at him.
You could say a husband's gift for his upset wife is an example of propitiation. Propitiation is an offering that appeases the wrath of someone.
Literally the word PROPITIATION means: "... the removal of wrath by the offering of a gift." 
The original idea of propitiation came from the pagans. In pagan religions, the word PROPITIATION meant "to offer a sacrifice to placate an angry god." For example, "When the king of Moab saw that the battle was too fierce for him, he took with him 700 men who drew swords, to break through to the king of Edom; but they could not. Then he took his oldest son who was to reign in his place, and offered him as a burnt offering on the wall. And there came great wrath against Israel, and they departed from him and returned to their own land. " (2 Kings 3:26--27).
"At noon Elijah mocked them, saying, "Cry aloud! Surely he is a god; either he is meditating, or he has wandered away, or he is on a journey, or perhaps he is asleep and must be awakened." Then they cried aloud and, as was their custom, they cut themselves with swords and lances until the blood gushed out over them. " (1 Kings 18:27--28).
The Christian meaning is much richer as we shall see today. Before we explore what Christian propitiation looks like we have to understand why God needs to be satisfied.
I. Why Does God's Wrath Need to be Satisfied?
A. God is holy
God is angry at sin because it offends His holiness and violates His holy Law. In His holiness, He must judge sinners. God cannot ignore sin or compromise with it, for that would be contrary to His own nature and Law.
B. We are not holy
"for all have sinned and fall short of the glory of God, " (Romans 3:23).
"All of us like sheep have gone astray, Each of us has turned to his own way... " (Isaiah 53:6).
"All of us once lived among them in the passions of our flesh, following the desires of flesh and senses, and we were by nature children of wrath, like everyone else. " (Ephesians 2:3).
C. God punishes the unholy
"For you are not a God who delights in wickedness; evil will not sojourn with you. The boastful will not stand before your eyes; you hate all evildoers. You destroy those who speak lies; the LORD abhors the bloodthirsty and deceitful. " (Psalm 5:4--6).
"God is a righteous judge, and a God who has indignation every day. " (Psalm 7:11).
"For the wrath of God is revealed from heaven against all ungodliness and wickedness of those who by their wickedness suppress the truth. " (Romans 1:18).
D. God loves mercy
God HATES sin, but He LOVES to show mercy. "The LORD is compassionate and gracious, Slow to anger and abounding in lovingkindness. " (Psalm 103:8).
"Who is a God like You, who pardons iniquity And passes over the rebellious act of the remnant of His possession? He does not retain His anger forever, Because He delights in unchanging love. " (Micah 7:18).
So this leaves us with a problem. God cannot pass over the sin of the unholy and still remain holy Himself. "The LORD is slow to anger and abundant in lovingkindness, forgiving iniquity and transgression; but He will by no means clear the guilty..." (Numbers 14:18).
"Behold, to the LORD your God belong heaven and the highest heavens, the earth and all that is in it. Yet on your fathers did the LORD set His affection to love them, and He chose their descendants after them, even you above all peoples, as it is this day. So circumcise your heart, and stiffen your neck no longer. For the LORD your God is the God of gods and the Lord of lords, the great, the mighty, and the awesome God who does not show partiality nor take a bribe. " (Deuteronomy 10:14--17). In other words, there is nothing we can do to turn God's wrath away from us.