“Anochi Hashem Elokecha” would seem to be a fundamental belief, in order to accept the rest of the Torah. To care about following the rest of the mitzvos,there must be a presuppositon that Hashem gave us those mitzvos.
Personal morality is very subjective. It fluctuates with the times in which a person lives. What was moral in one generation may no longer be thought to be necessary in a future generation. Just look at the new marriage laws enacted in NY State recently.
The only true morality is that which Hashem has told us is moral and just. Though there are some discussions as to the intent and exact meaning of certain halachos, with some people’s hashkafos differing from others, the basic halachos which all frum people typically follow, remain unchanged since the time of Moshe Rabeinu. Time and generation have not altered the Torah. And that’s the difference.