Chapter 1 considers the fear of atheism that gripped early modern thinkers, assessing its nature and extent and seeking to explain its rationale; in the course of this, its association with trends in the thought of the period such as naturalism, secularism and Deism is considered, as is its supposed link with immoralism. The chapter also asserts that the few well-documented examples of actual atheists that are known from the period were characterised by the ‘assurance’ that they showed in propagating their views, in contrast to the doubts suffered by Christian believers, a point that is illustrated by recourse to the history of emotions. The remainder of the chapter summarises the content of the rest of the book, paying particular attention to the Cerne Abbas enquiry of 1594 and to the apostacy of Christopher Marlowe and of John Eliot in Edinburgh in 1694.