A person at the Yahoo! Answers asks, "Why must we have religion?" I think that my reply is worth posting here:
People don't need religion. However, they do need philosophy; they do need a fundamental view of existence and values in order to live their lives. Unlike other living creatures, human beings are not born with any values to guide their choices and actions. All the values they hold, they must aquire either by conscious decision or by unconscious acceptance.
To quote philosopher, Ayn Rand, "As a human being, you have no choice about the fact that you need a philosophy. Your only choice is whether you define you philosophy by a conscious, rational, disciplined process of thought and scrupulously logical deliberation--or let your subconscious accumulate a junk heap of unwarranted conclusions, false generalizations, undefined contradictions, undigested slogans, unidentified wishes, doubts and fears, thrown together by chance, but integrated by your subconscious into a kind of mongrel philosophy and fused into a single, solid weight: self-doubt, like a ball and chain in the place where your mind's wings should have grown." - Philosophy, Who Needs It? http://gos.sbc.edu/r/rand.html.
According to Rand, religion is an early form of philosophy which arose before humans could develop a scientific approach to the fundamental questions of life that philosophy must address. Today, religion is still the only form of philosophy most people know about. Furthermore, many people feel devotion to the religion they were taught as children since they associate that religion with the love they feel towards their parents. And while religion can have important values to teach and many worthwhile lessons to learn, it does not fulfill the human need for an objective comprehensive view of life, since it is based upon the pre-scientific and invalid approach of faith and the ancient destructive moral code of self-sacrifice. Moreover, modern academic philosophy has, over the past two hundred years, become a mostly useless psuedo-science that does not deal with the questions and problems human beings actually face in life.
I recommend Ms. Rand's philosophy called Objectivism as a rational alternative to religion, academic philosophy, cynical hopelessness, and unserious self-imposed blindness. There is a tremendous amount of information on the internet about her writings and philosophy that you can investigate. I recommend starting out at the Ayn Rand Institute: http://www.aynrand.org. And if you become interested, you can look into purchasing her novels and/or non-fiction works. Another accessible introduction to her ethics is called, Loving Life: The Morality of Self-Interest and the Facts that Support It by Craig Biddle. This book is available at Amazon.com.
To give you a quick introduction to her philosophy, I will quote Ayn Rand again, "My philosophy, in essence, is the concept of man as a heroic being, with his own happiness as the moral purpose of his life, with productive achievement as his noblest activity, and reason as his only absolute."