You are trying to make a rational argument for altruism without God and now you claim not to care if you can make an argument to the thief regarding why he should not steal. You don’t care how he feels. Some athiest Sunday school teacher you would make!
That's just silly. Your argument is that people should not sin because your God says not to. Please go out and try to convince inner-city muggers of that. You wouldn't last a day. Does that mean you're wrong?
You seem to think the validity of morality depends on one's ability to convince others of it. That only work if morality is relative. Judeo-Christian morality is competing with Muslim morality and right now Muslim morality is winning by the numbers. Does that mean you are wrong about what is good and evil?
The strength of my basis for morality is that it is an absolute morality, unlike standard Judeo-Christian morality, which is basically inconsistent and internally conflicted.