In the nineteenth century, many American Christians yearned to restore the church to the simplicity and vitality of its New Testament origins. These restorationist movements spearheaded American church growth well into the twentieth century. One of these groups, known as the Church of God, was led by a holiness preacher named Daniel Sidney Warner (1842-1895), who preached a radical message of Christian unity and personal holiness. Warner challenged believers to leave their rival denominations because they were all one in Christ. These "come outers" held no formal church membership, no governing church officials, and recognized no ministerial credentials. Instead of having an ecclesiastical hierarchy, they emphasized the priesthood of all believers. They began several innovative ministries--rescuing young women caught in sex trafficking, distributing food and teaching children in crowded cities, and lobbying for the pardon of prisoners on death row. Now headquartered in Anderson, Indiana, the Church of God has nearly a million adherents worldwide. This narrative of D.S. Warner's life and ministry reveals that not all Christians of the Gilded Age stood aloof from the human needs of their day. The sacrificial, courageous work of this frontier evangelist still challenges Christians today.