Simone de Beauvoir was a French writer, existentialist philosopher, feminist, and social theorist. She is considered the mother of post-1968 feminism, and her treatise The Second Sex was a defining work. She is also famous for her metaphysical novels, including She Came to Stay and The Mandarins. She was part of the tight intellectual circle in France which included Jean-Paul Sartre, and is thought to have influenced his masterwork, Being and Nothingness. 
In a New York Times article from May 27, 2010 entitled Introduction to Simone de Beauvoir's 'The Second Sex', it states:
"Beauvoir herself was as devout an atheist as she had once been a Catholic, and she dismisses religions — even when they worship a goddess — as the inventions of men to perpetuate their dominion."