For he himself is our peace, who has made us both one and has broken down in his flesh the dividing wall of hostility
Jesus doesn't just come and give peace as if it is some sort of mysterious substance or force. He IS our peace. His broken body has broken down the walls of hostility between us and God and between each other. There is no true, lasting peace without him. Peace that surpasses understanding, peace that is not dependent on circumstances, is only found in Jesus.