Well, then, on that basis I guess you'd have to toss out any conception of morality that does not follow the empirically observable facts of nature.
Of course, that would only leave us with relativist moralities like Utilitarianism, Social Darwinism, and Might Makes Right -- but hey, what the heck, it's scientifically based, right?
As it happens, religion is an exceedingly good basis for certain types of argument. What's an exceedingly bad argument is to take your approach, and to irrationally rule out the possible existence of God.
You are a very foolish (and stubbornly so) person. You put all of your faith in science yet science can't answer all questions. Science is about observation and application... it deals with the "what" of life. What happened? What will happen if these circumstances are repeated?
Indeed philosophy and religion have always been the basis of the arguments of life.
Philosophy and religion seeks to answer the far more important question... why. I think post #127 does an excellent job of taking this argument further so I won't simply repeat what has been well laid out for you.