On 11 September 1697, Christianity not Mysterious was burned in Dublin by order of Parliament. Three hundred years later, this seminal text of Irish - and European - philosophy becomes available in a new scholarly edition, along with John Toland's defences of his work and eight critical essays by leading scholars. Born into a Catholic, Irish-speaking family on the Inishowen peninsula of Co. Donegal, John Toland (1670-1722) became a Protestant as a teenager; he later embraced deism and became the first exponent of pantheism. Christianity not Mysterious, first published in 1696, argues that 'there is nothing in the Gospels contrary to reason' and that the so-called Christian mysteries are merely the inventions of competing sects - a view that threatened the very basis of the supremacy of the Established Church in Ireland. Toland left Ireland under threat of arrest and spent the remainder of his life in Britain and on the continent, where Christianity not Mysterious was enormously influential. Toland's advocacy of reason over revelation in Christian belief went further than Locke and other previous rationalists, and provoked a distinguished Irish counter-Enlightenment tradition that included Swift, Berkeley, Burke and many others. The first great work of Irish philosophy since the writings of Ériugena in the ninth century, Christianity not Mysterious is a dazzling piece of rhetoric, by a gifted controversialist. The critical essays establish Toland's central position in the theological and scientific debates of the early Enlightenment, and make a case for his continuing relevance to the vexed questions of Irish and European identities.