Modern morals are a mixture of two elements: on the one hand, rational precepts as to how to live together peaceably in a society, and on the other hand traditional taboos derived... proximately from sacred books... To some extent the two agree... As soon as we abandon our own reason, and are content to rely upon authority, there is no end to our troubles. Whose authority? The Old Testament? The New Testament? The Koran? In practice, people choose the book considered sacred by the community in which they are born, and out of that book they choose the parts they like, ignoring the rest.

Bertrand Russell