Losing Share of Olam Haba
Question
I just read that one who disgraces Chol Hamoed loses their share in Olam Haba. I have also read the same about many other acts. Suppose one is well compliant with every law of the Torah, except for one, and the one law he fails to observe is one that it is taught one loses their share in Olam Haba. Does he still lose his share in Olam Haba, even if he observed every other mitzvah perfectly?