Is a non-Jew forbidden from lying? What if he only engages in deception but not out right shekel? For example, could a non-Jew who used to be a idol worshipper but who now follows the sheva mitzvot keep his new beliefs concealed from his idol-worshipping family, in order to be saved from the stress and poor family relations, knowing his family would still believe him to be an idol worshipper as well?
Without getting into the technical halacha if it is permitted of not, lying is a terrible habit, and erodes the very fabric of society, and should be shunned. On the otherhand there is no need for him to disclose to his family that he now has new beliefs and that he is no longer an idol worshipper.