Sigmund Freud was a proponent of atheism who argued that theism was detrimental to mental health.<ref name="christtoday">McGrath, Alister (February 28, 2005). [http://www.christianitytoday.com/ct/2005/003/21.36.html "The twilight of atheism"]. ''Christianity Today'' website. Retrieved on May 23, 2015.</ref> [[Oxford]] Professor [[Alister McGrath]], author of the book ''The Twilight of Atheism'', stated the following regarding Freud:
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Sigmund Freud was a proponent of atheism who argued that [[theism]] was detrimental to mental health.<ref name="christtoday">McGrath, Alister (February 28, 2005). [http://www.christianitytoday.com/ct/2005/003/21.36.html "The twilight of atheism"]. ''Christianity Today'' website. Retrieved on May 23, 2015.</ref> [[Oxford]] Professor [[Alister McGrath]], author of the book ''The Twilight of Atheism'', stated the following regarding Freud:
{{cquote|One of the most important criticisms that Sigmund Freud directed against religion was that it encourages unhealthy and dysfunctional outlooks on life. Having dismissed religion as an illusion, Freud went on to argue that it is a negative factor in personal development. At times, Freud's influence has been such that the elimination of a person's religious beliefs has been seen as a precondition for mental health.
{{cquote|One of the most important criticisms that Sigmund Freud directed against religion was that it encourages unhealthy and dysfunctional outlooks on life. Having dismissed religion as an illusion, Freud went on to argue that it is a negative factor in personal development. At times, Freud's influence has been such that the elimination of a person's religious beliefs has been seen as a precondition for mental health.