Parashat Kedoshim opens with the Mitzvah of “Kedoshim Tihyu.” The Meforshim offer many interpretations of this enigmatic phrase. Rashi explains this to mean that Bnei Yisrael should separate themselves from Gilui Arayot, immorality, and through this be sanctified. Ramban proposes that this injunction may refer just to a general sense of self-restraint. One might think it sufficient to observe the letter of the law and permit himself to indulge in all kinds of technically permitted behaviors, therefore this Pasuk teaches, in Ramban’s view, that it is prohibited to be a “Naval Birshut HaTorah,” “Despicable person with the Torah’s permission.” Enjoying life is acceptable, but Hashem does not want us to overindulge, lest it lead to other inappropriate activities.
Rav Moshe Feinstein offers a different approach. He writes that the reason for the commandment to be Kadosh is in the nature in which all Mitzvot were designed. While general society tries to dissuade people from doing evil by meting out punishments, the Torah has a different system. Rav Moshe says that Hashem gave us the Mitzvot so that our society could improve itself, not just to protect the victimization of its citizens. The commandment to be Kadosh means that we should improve ourselves so that we want to perform Hashem’s Mitzvot so as to improve ourselves.