"Heretics" by G. K. Chesterton is a collection of essays published in 1905. In twenty provocative chapters, Chesterton challenges the leading intellectuals of his era, including George Bernard Shaw, H. G. Wells, and Friedrich Nietzsche. He critiques atheism, nihilism, Social Darwinism, and eugenics while defending orthodox Christianity. His arguments span cosmology, anthropology, and theology, taking aim at what he sees as the dangerous philosophies shaping modern thought. Together with "Orthodoxy," this work forms the foundation of Chesterton's moral theology.