You mentioned Freud for a moment there.  I just wanted to mention that Freud wrote a book way back in 1927 called 'The Future of an Illusion".  I read this book about a month ago and would definitely recommend it to anyone interested in religion and psychology.  It is considered to be Freud's "indictment" of religion.  Throughout his adult life, Freud often referred to himself as a "godless Jew" which I can't help but find amusing.  This is not the only book he wrote on religion but it is the only one I have read and can recommend.  Also, its fairly short and you don't have to be well versed in psychology at all to understand it.