Moral values and duties is often misconstrued in the exact way that you described, namely, without God or religion, there would be no morals. However, the question of moral values and duties has to do more with moral epistemology--the explanation of how morals arose vs moral ontology--how morals really are. And it is in the ontological sense of morals that seems to be debated the most which consists of mainly two sides; relative and objective moral values and duties.
The objectivist postulates that without God, morals have no ontological objective status. That is to say, there is nothing to ground the moral values and duties that we all abide by thereby morals wouldn't be objective. While the moral relativist postulates just the opposite; moral values and duties change throughout culture, and thus, have no objective status to speak of. The only grounding is us; we say what is right and wrong.
So, with this in mind, let's examine your inquiry.
You say, "So what if some ridiculous event occurred tomorrow that proved the non existence of god, would you all turn into murderers and rapists? Or would you be exactly the same people."
I would answer this question in the following way: I wouldn't turn into a murderer or a rapist but I don't see how or why I would have to follow someone else's morals; after all, moral values and duties would at that point be up to me. What I say goes. For, who could tell me that I'm wrong for any actions I commit? The court? My fellow man? Why? How? They don't have any more moral high ground than me. So who are they to tell me what's right or wrong? I'm perfectly capable of deciding what is right and wrong for myself.
If this makes no sense to you, causes something to rise up within in, or goes against what you believe about morals; it is exactly what we're left with if there is no objective ontological grounding for our moral values and duties.
I hope that this suffices as an answer and that someone learned a little bit about the debate about moral values and duties that has been and will most likely continue to be debated for centuries to come!
