One-shot refutation of moral dogmatism
Here is the one-shot refutation of any moral dogmatism, be it based on "religion", "the commandments", "the law", or any other doctrine that people claim is necessary for morality.
When they tell you : "If people didn't have X, they would just go around raping and killing people. How could you stop anyone from coming in your home, killing you, and stealing all your possessions?"
Ask this : "If YOU didn't have X any more, WOULD you go around raping and killing people? Would you come in my home, kill me, and steal all my possessions? YES OR NO?"
By tearing down their pretense of "people are like this or that", you reduce them to an unsavory choice : either they are the only moral person on the planet, which is impossible, or they were dead wrong.