So we should be free to invent our own moral and philosophical authority based on your own viewpoints , wonder where we would be if everyone did that, some would consider it fine to kill rape and murder others wouldnt , but no legal system etc as we are all free to do as we please.
You present a false choice. Morals can be completely independent of religion. In fact, even in western society, societal moral codes are decidedly not derived from the bible(!) The bible sets out hundreds of moral codes, but very few are followed today. When was the last time you refused to share the bed with a menstrating woman?
Japan, an essentially athiest society, has very similar moral codes to christian nations - prohibitions against murder, rape, etc. Morality is very simple - not harming your fellow human. Christian morality says it is ok to harm your fellow human, as long as god says it is ok. In fact, I would say that secular humanism and natural rights theory are more moral that christian morality because there are no special exemptions from respecting your fellow man. Stoning unruly children is expressly endorsed in the bible. I say that stoning children is wrong, no matter what.