"The Necessity of Atheism" is an essay on atheism by the English poet Percy Bysshe Shelley, printed in 1811 by Charles and William Phillips in Worthing while Shelley was a student at University College, Oxford.

Percy Bysshe Shelley was a British writer who is considered as one of the major English Romantic poets. A radical in his poetry as well as in his political and social views, Shelley did not achieve fame during his lifetime, but recognition of his achievements in poetry grew steadily following his death, and he became an important influence on subsequent generations of poets, including Robert Browning, Algernon Charles Swinburne, Thomas Hardy, and W. B. Yeats. American literary critic Harold Bloom describes him as "a superb craftsman, a lyric poet without rival, and surely one of the most advanced sceptical intellects ever to write a poem."