The Age of Reason; Being an Investigation of True and Fabulous Theology is a book written by the British and American political activist Thomas Paine. The book defends the philosophical position of deism, follows in the tradition of 18th-century British deism, and challenges the official religion and the authority of the Bible. It was published in three parts in 1794, 1795, and 1807.
The Age of Reason waas a best-seller in the United States, where it was the cause for a coming back of deism. However, it was not well received in Britain because the public there feared increased political radicalism as a result of the French Revolution.
The Age of Reason presents common deistic arguments; for example, it highlights what Paine saw as corruption of the Christian Church. He prefers reason to revelation, which leads him to reject miracles and to view the Bible as an ordinary book, rather than a text given by God. He promotes natural religion and argues for the existence of a creator god.