The Divine Son - Faith in Christ
Propitiation is something that Christ has done for the entire world. That means that God is at peace with this world concerning its sin. The only question that remains is, what is the world going to do with the Savior? The issue is not human sin, but the Son of God. The world has a Savior who has satisfied God.
My little children, I am writing these things to you that you may not sin. And if anyone sins, we have an Advocate with the Father, Jesus Christ the righteous; and He Himself is the propitiation for our sins; and not for ours only, but also for those of the whole world (1 John 2:1-2).
The world has a Savior, and we have an advocate through our faith in Jesus Christ. He is in heaven as our great high priest to protect us to the utter most. What saves a person is faith in Christ. Christ has satisfied God concerning human sin, but now humanity has to exercise faith in Christ to be right with God.