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...