Histakel b’Oraisa uvara alma.
HKB”H created morality, and gave people the ability to tune into it. Avraham Avinu did the ultimate in this regard; he kept kol haTorah kulah without a direct tzivui because he reached such a high level that his ratzon was in sync with Hashem’s.
Asking what the world would look like without Hashem (or what morality would be) is an exercise in futility. It’s like asking what would the ocean be without water. It’s definitionally impossible.
What is a little more reasonable to ask is how much morality can one have without knowing any Torah. I doubt we’re held responsible for not achieving what Avraham Avinu did, but I think a certain level of morality is expected, such as not killing, not stealing, and arayos. It comes from an inherent sense of right and wrong which Hashem granted to human beings, which on its most basic level manifests itself in what we refer to as “morality”.
Talking about morality without Hashem, or talking about anything without Hashem, is futile, because nothing exists or can exist without Him, not even “in theory”.