I also recommend that time be spent with the recently released Evangelical Manifesto: A Declaration of Evangelical Identity and Public Commitment.
Read the six page Executive Summary if you are pressed for time. The full statement is 20 pages and deserves all of the time and consideration you can give. The money paragraph for me was this:
Evangelicalism must be defined theologically and not politically; confessionally and not culturally. Above all else, it is a commitment and devotion to the person and work of Jesus Christ, his teaching and way of life, and an enduring dedication to his lordship above all other earthly powers, allegiances and loyalties. As such, it should not be limited to tribal or national boundaries, or be confused with, or reduced to political categories such as "conservative" and "liberal," or to psychological categories such as "reactionary" or "progressive."