Question: Which book was written by an atheist salon owner and explicitly denies the existence of God?

Kafir (Arabic: كافر‎ ‎ "kāfir "; plural كفّار "kuffār "; feminine كافرة "kāfirah ") is an Arabic term (from the root K-F-R "to cover") meaning "unbeliever", or "disbeliever".  The term alludes to a person who rejects or disbelieves in God and the teachings of the Islamic prophet Muhammad, and denies the dominion and authority of God; or otherwise does not heed the beliefs and prescriptions held by the religion of Islam.  It is used as a derogatory term.  Unbelief is called "kufr".  "Kafir" is sometimes used interchangeably with "mushrik" (مشرك , those who commit polytheism), another type of religious wrongdoer mentioned frequently in the Quran and Islamic works.  The practice of declaring another self-professed Muslim a kafir is known as "takfir".  The person who denies the existence of a creator is called "Dahriya". <SEP> The System of Nature or, the Laws of the Moral and Physical World ("Système de la Nature ou Des Loix du Monde Physique et du Monde Moral") is a work of philosophy by Paul-Henri Thiry, Baron d'Holbach (1723–1789).  It was originally published under the name of Jean-Baptiste de Mirabaud, a deceased member of the French Academy of Science.  Most notoriously, the work explicitly denies the existence of God, arguing that belief in a higher being is the product of fear, lack of understanding, and anthropomorphism.  D'Holbach wrote and published this book – possibly with the assistance of Diderot but with the support of Jacques-André Naigeon – anonymously in 1770, describing the universe in terms of the principles of philosophical materialism: The mind is identified with brain, there is no "soul" without a living body, the world is governed by strict deterministic laws, free will is an illusion, there are no final causes, and whatever happens takes place because it inexorably must. <SEP> Paul-Henri Thiry, Baron d'Holbach (] ), was a French-German author, philosopher, encyclopedist and prominent figure in the French Enlightenment.  He was well known for his atheism and for his voluminous writings against religion, the most famous of them being "The System of Nature" (1770).  He was born Paul Heinrich Dietrich in Edesheim, near Landau in the Rhenish Palatinate, but lived and worked mainly in Paris, where he kept a "salon". <SEP> Deism, the religious attitude typical of the Enlightenment, especially in France and England, holds that the only way the existence of God can be proven is to combine the application of reason with observation of the world.  A Deist is defined as "One who believes in the existence of a God or Supreme Being but denies revealed religion, basing his belief on the light of nature and reason."  Deism was often synonymous with so-called natural religion because its principles are drawn from nature and human reasoning.  In contrast to Deism there are many cultural religions or revealed religions, such as Judaism, Trinitarian Christianity, Islam, Buddhism, and others, which believe in supernatural intervention of God in the world; while Deism denies any supernatural intervention and emphasizes that the world is operated by natural laws of the Supreme Being.