Shlomo told a story about a man he met going to a mikvah (in Waco, Texas!) boerfe Shabbat who was obviously not religious. This man immediately addressed Shlomo as to why he was there. When he was a child, his rabbi had urged him most strongly not to listen to the lie that because he had sinned, that he could not be holy for one moment.The commandment to separate Sabbath is its own commandment. You can be holy for the one moment of Havdalah.