You don't need a god to have an absolute morality. I'd say it's pretty irrelevant, actually.

Let's assume there is a god, and that stealing is wrong.

Now, the question is

A) is stealing wrong because there's some absolute moral principle, a universal moral law not unlike the universal laws of physics or the like? In this case, your omniscient god is aware of these laws and might reveal them to mankind, but doesn't actually create them

or

B) stealing is wrong because god says it's wrong. There's no intrinsic value to it other than that.

The (B) choice actually eliminates absolute morality. It says something is right only because a tyrant-figure creates and enforces it. If that entity would decide that setting children on fire is the new moral right, so would it be. That's pretty subjective and relativistic.