More than one person has joked over the years that Evangelical believers do not have an ecclesiology. In one sense, that is absurd: Evangelical churches (especially if you include Pentecostals in that group) are some of the fastest-growing, most vibrant churches in the world. Evangelicals are proclaiming the gospel, praising the Lord, reading the Bible, and loving the poor. But there is a case to be made that the Evangelical devotion to the mission...