From J.I. Packer’s book, Knowing God (1973):
Too often the peace of God is thought of as if it were essentially a feeling of inner tranquility, happy and carefree, springing from knowledge that God will shield one from life’s hardest knocks. But this is a misrepresentation….
The peace of God is first and foremost peace with God; it is the state of affairs in which God, instead of being against us, is for us. No account of God’s peace which does not start here can do other than mislead. One of the miserable ironies of our time is that whereas liberal and radical theologians believe themselves to be restating the gospel for today, they have for the most part rejected the categories of wrath, guilt, condemnation and the enmity of God, and so have made it impossible for themselves ever to present the gospel at all, for they cannot now state the basic problem which the gospel of peace solves.
The peace of God, then, primarily and fundamentally, is a new relationship of forgiveness and acceptance, and the source from which it flows is propitiation.