Morality Doesn't Come From Any Book

Most christians would say that the Bible is the basis for their moral views. Some would even go so far as to say that a person can't be moral without believing in the Bible. I have serious questions about the validity of that. Did morality not exist before the Bible was written? Of course it did. Writings of the Sumerians, Greeks, and others show a definite morality, and in fact, a reasonable argument can be made that the Bible got much of it's morality (and stories) from older writings.

The truth is that while the Bible contains many valid moral teachings, it also contains some that are no longer valid (and acceptance of slavery is only one of them). The world has changed (for the better) in the thousands of years since the Bible was written. The Bible can no longer be considered the be all and end all for moral guidance -- especially since modern christians must pick out some parts and discard others to create a morality for current times.

Do we really need a book, any book, to tell us what is right and what is wrong? Is it not obvious that doing things that help others is right and doing things that hurt others is wrong? With the exception of a few sick individuals (like sociopaths), haven't we, and society in general, always known that?