Feeling separated from God is a lonely place to be. Many circumstances can cause it: busyness, trials, lack of direction. We feel frustrated; our faith stagnates. But there is a way back, an ancient way that leads us to new union with God. "Long ago," Calvin Miller writes, "when the Celts built their own rustic kingdom of God in Ireland, Scotland and Wales, their fervour in prayer washed their world in the vitality of revival." In uncertain and dangerous...