The Hebrew word for peace is shalom and is broader and more all encompassing than the modern understanding of well-being. Positively, it means wholeness or completeness. Negatively, it means the absence of conflict within ourselves, with others, and in the world.
However, without peace with God vertically, there is no peace internally or horizontally. How do we experience peace at Christmas? We first have to acknowledge our hostility with God. Only when we realize God is our problem can he also become our solution. When we do, we begin to see how God works peace on our behalf.