Question:
I am ruthless and stone cold with nonjews. Does that constitute Chillul HaShem if one of them learns that I am a Jew ?
Answer:
If people know that a Jew is acting incorrectly, it can be a chilul Hashem. However, we always have to know that we are capable of changing our behavior, and if you will act nicely to people from now on, that will be a Kiddush Hashem.
Best wishes