In Vigilant Faith: Passionate Agnosticism in a Secular World, Daniel Boscaljon takes up the contemporary challenges to faith by skepticism and secularism. He proposes a model of faith for believers and unbelievers alike—a passionate agnosticism—that is rooted in a skeptical consciousness. Skepticism and faith are structurally similar, he writes, in that they share an "unknowing" quality. The author argues that vigilance—the act of keeping watch, a spiritual practice in its own right—is as necessary a precondition for the structure of faith as it is for the structure of skepticism. A suspension in uncertainty and an openness to possibility require vigilance, he attests, if faith and skepticism are to avoid the often dogmatic tendencies of both theism and atheism to cling to their own brands of certainty and knowledge.

Boscaljon has three aims: to expand the current, post-theistic definitions of God for greater relevance to human beings on an individual and existential level; to integrate skepticism into faith so that it will restore the importance of faith to current theology and recover it from anti-intellectual bias; and to conceptualize the vigilance of faith in such a way that can provide a vocabulary for distinguishing "good faith" from "bad faith." He offers a variety of cultural examples ranging from film to poetry to represent a life of faith and to show how its components come together in practice. As an alternative to the prevailing fundamentalisms in today's world, his book proposes a paradigmatic understanding of faith in which theism, atheism, and agnosticism refuse to differ.