The book does some things well.
It is well-organized, especially in the format of each of the chapters, identifying and enumerating the main ideas in such a way as to make the book easy to read and assimilate.
It focuses upon theology proper, christology, and pneumatology from the whole of Scripture—particularly as these shape the visible church's role in God's ongoing work in the world. And it does a good job with both of these things.
The book traces its biblical theology from the whole of scripture and properly identifies and employs many of the most relevant specific texts to show this theology.
It does justice to the fact that the mission belongs to God and is accomplished by His activity and power. Too many other works on the subject fail to properly acknowledge, and yield to, the necessarily supernatural essence of what we pray and hope will occur as we bear witness.
Among its many emphases, the book has a much-needed emphasis upon how the church's witness (its part in God's mission) consists most of all on just being the church, as He has designed and called it to be. The greatest need, therefore, is reformation. Sanctification. Revival.
I don't envy the task of trying to tackle such a large subject. But there are some things that the book does not do well. These are largely in the areas of what it does not address.
Considering the need for revival, in order to Bear biblical witness, the book does some good work in describing what the fruit of revival looks like. But it is a little lacking in describing what that revival is, and more lacking in describing how it happens. We cannot have congregational reformation without household reformation, and we cannot have household reformation without personal reformation. The biggest defect in the church's witness is men whose selves and lives are not beacons of union and communion with Jesus Christ, by His Spirit, unto communion with God.
Another lack is in failing to distinguish the role of the Christian from the role of the congregation. This is especially glaring in a few of the items that he repeatedly identified as the "church's witness," particularly: "gospel global partnerships, [...] compassion ministries, biblical counseling, cultural engagement." Several items that Scripture handles entirely with reference to individuals with their neighbors, are listed in a way that fails to correct the confused state of the church in which the congregation attempts to function as a citizen or neighbor, which it is not.
One more weakness that bears mentioning is that the book at times has an ax to grind with what it considers a failure to contextualize, sometimes described as a confusion of the Gospel with the exporting of Western European culture. This familiar trope is unhelpful, because it fails to recognize that much of what is now known as Western European culture is not the original culture of Western Europe but the consequence of gospel transformation. Exhortations to contextualization need to be strongly tempered by the fact that culture is an aggregate of individuals and personalities, and the biblical response to it is always some form of correction, most of all. Adaptation is not an exercise in figuring out how the culture should shape gospel expression, but rather identifying unnecessary corrections that the gospel must bring to that culture.
In my view, the most glaring weakness is the absence of a thorough doctrine of ordination and a thorough ecclesiology. Faith comes by hearing, and particularly by hearing those who are sent. Since the mission is God's (while the witness is ours), and God Himself ordains and sends particular preachers particularly, a biblical implementation of witness demands a functional submission to a thorough doctrine of biblical ordination. And Scripture describes a mission of God in which He is not just saving but planting churches, not just planting churches but planting presbyteries. This may be intentional, since thinking and writing in this way significantly narrows the proportion of the visible Church that would welcome the book as things currently stand. But how can these deficiencies in the church be corrected, if in order to get a wider reading audience, they become deficiencies in the book?
Finally: do not let these weaknesses dissuade you from reading the book. First of all, it is an easy read. Secondly, it is a worthwhile read—it does as good a job of a biblical theology of the witness that the church bears to Christ as any book that I am aware of.
