Ethics, the first volume of McClendon's Systematic Theology, explored the shape of life in the Christian community.

Doctrine, the second volume, investigated the teaching necessary to sustain that life. Witness, the third and final volume of the work, considers the wider context in which that life takes place. It asserts that the church's identity is established not only by how it lives and what it teaches but also by how it enters into conversation and connects with systems of thought and social structures outside itself.

McClendon continues here his exploration of "the baptist vision", a tradition of the church's understanding of itself, its relation to Scripture, and its place in the larger society, which flows from the Radical Reformation of the 16th century.

He employs that vision to engage in conversation with three principal partners: other theologies; current philosophy; and culture, including science and letters, the fine and performing arts, and politics - in short, what Scripture calls "the world".