Today on the Leonard Lopate show a memoirist and novelist named John Marks was featured in a segment called A Former Evangelical's Crisis of Faith.  Lopate and Marks, who are both not practicing Christians, showed a stunning secular understanding of American Protestantism, being that they are outsiders.  It helped that Marks had been an evangelical before leaving Christianity altogether, but Lopate also showed a surprising knowledge of the differances between charismatic and Pentacostal expressions of faith and worship.  In summary, the segment discussed how:

American evangelical Christianity can be misunderstood by outsiders.  Veteran journalist and former 60 Minutes producer John Marks was born again at age 16, but later abandoned his faith.  His new book about the religion he left behind is Reasons to Believe: One Man's Journey Among the Evangelicals and the Faith He Left Behind. 

Lopate asked Marks about the differences he saw between Fundamentalism, Evangelicalism, and Pentacostalism, and Marks's answer was insightful and perhaps enlightening.  To paraphrase, Marks answered:

"In discussing these strands of faith one must look at the Trinity.  Fundamentalists stress the Old Testament, biblical innerancy, and prophecy, so they emphasize God the Father over the other persons.  Evangelicals stress evangelism and the person of Jesus in the individual's life.  Pentacostals stress healing, tongues, and contemporary revelation, so they naturally hold the Holy Spirit above the other persons.  Each of these groups has favored one part of the Trinity over the other."

I think Marks's critique makes a lot of sense, especially when compared with the reforming work of someone like Stanley Grenz.  Grenz, makes the point in his "systematic" Theology for the Community of God that every doctrine must start with the realization of God and that his nature is triune.  One of the worst flaws of American Protestantism is the loss of trinitarian concepts, that in the wake of modernism Christianity became genre-based along Trinitarian lines, as if the catholic faith became splintered like Rock & Roll into Alternative, Hard Rock, and Emo.

The Unity of God must be recovered in American Protestantism, and I think that starts first and foremost with the uniting of the Body of Christ.