'A Tale of a Tub' was the first big work written by Jonathan Swift. It is arguably his most difficult satire, and perhaps his most masterly. The Tale is a prose parody which is divided into sections of "digression" and a "tale" of three brothers, each representing one of the main branches of western Christianity. Composed between 1694 and 1697, it was eventually published in 1704. 'A Tale' was long regarded as a satire on religion itself, and has famously been attacked for that, starting with William Wotton.
The "tale" presents a consistent satire of religious excess, while the digressions are a series of parodies of contemporary writing in literature, politics, theology, Biblical exegesis, and medicine. The overarching parody is of enthusiasm, pride, and credulity. At the time it was written, politics and religion were still linked very closely in England, and the religious and political aspects of the satire can often hardly be separated.