In his sermon series “What is the gospel and how does it work?” Don Carson makes the point that Jesus’ death on the cross is propitiation, and not expiation only, as many have argued.
Expiation is simply the taking away or the cancelling of sin. Propitiation is that sacrificial act by which God becomes propitious — that is favourable.
Our biggest problem is that we are sinners and that our sin is against God. The result is that we incur God’s righteous wrath.
Expiation alone takes away sin which is necessary, but it doesn’t deal with the problem of God’s wrath.
The cross is so powerful because there Christ was put forward as a propitiation. As a result God is made favourable. And this includes expiation — the taking away of sin. (The interesting thing is that nowhere do we see a dynamic where man offers God something that makes him propitious. Here God is doing all the work himself.)
God offers sacrifice to make God propitious. That is the gospel. Because God stands over against us in wrath because of our sin and our guilt. [Paul spends] Two and a half chapters to establish that point. But God stands over against us in love because he is that kind of God.
And how do you put it together?
He stands over against us in wrath not because he’s bad tempered like neptune and has to be manipulated by an appropriate sacrifice for which you pay a fee in a temple where we offer the propitiation. God is bad tempered, and if somehow we can just offer the right sort of sacrifice, do the right sort of self denial, have our devotions properly, somehow God will be propitious [favourable].
He stands over against us in wrath not because he is bad tempered or whimsical, but because we are guilty. We are idolators, and there is no one righteous. No, not one. And the wrath of God does abide on us. But he stands over against us in love not because we’re so intrinsically loveable, but because he’s that kind of God. Full of compassion, plenteous in mercy. He will not always chide. He is the God who cries “turn, turn, why will you die?” The Lord has no pleasure in the death of the wicked.
And then in the fullness of time he sends forth his son, presenting him as the propitiation for our sins. That is the one who sets aside God’s wrath. God himself provides the sacrifice that satisfied God’s own sense of justice and sets aside God’s wrath.
Now in fact that is done by cancelling sin and its debt so there is expiation that takes place. That is, in the one act there is both propitiation and expiation.