Witherington's The Problem with Evangelical Theology both introduces and criticizes the exegetical basis of foundational claims in the various traditions that make up American evangelicalism. Whether or not you agree with Witherington's conclusions, you should agree that they amount to a challenge to a tradition that you belong to or are familiar with. His challenge is worth meeting.
Pretend that over the past couple of weeks you have struck up a conversation with a real pastor or teacher you know who belongs to one of the traditions Witherington addresses: Lutheran Augustinianism, Calvinist Augustinianism, Dispensationalism, Wesleyan Arminianism, or Pentecostal Holiness.
Now that you are finished with the book, write a letter to that person advising the recipient on how you think he or she should respond to Witherington's arguments exegetically, theologically, and pastorally. I want to see all three aspects in your response.
For the sake of brevity — i.e., so summary rather than analysis does not dominate your letter — you may assume that you have filled that person into the general substance of Witherington's argument in your earlier conversations. You will want to allude to them, though, so your recipient will know what specific arguments your advice addresses (and so I will know that you understand the arguments!).
You may also want to treat Witherington's general assessments of evangelicalism (in the beginning and end of the book) as well as the specific arguments he addresses to that specific tradition.
Please keep your letter 3-4 pages, double-spaced, and follow the directions in my handout for writing papers. Remember, I want to see proper style, clear writing, a thorough answer to the question, and explicit citations of course materials.