At the time, I made a distinction between ethics and morality that I would now say is probably more semantic than definitional. But, IIRC, they defined morality as a code of behavior with a religious basis. So I used the term ethics to say that I followed a code of behavior that didn't follow from religious belief.

Essentially, I made the point that just because I didn't believe I would go to hell for killing somebody didn't mean that I had any desire to. Or that the prospect of prison and general rejection from society didn't serve as an adequate deterrent. I don't remember specifically, but I might have made the point that the Golden Rule doesn't have to be tied to a religious belief and is a pretty self evident truth on its own.

As for their response, I mostly remember them moving onto a different topic (or at least, ceasing to focus on me for that moment). I always thought about my answers and tried to give an honest answer, but I actively avoided giving them the answers they were expecting or wanted, since they were usually leading questions designed to get me to agree with them in some basic way.