Objective morality doesn’t exist. Even if it did that doesn’t necessitate a God. Let’s use colors for a stand-in to morality, now you have two colorblind people arguing whether objective color truly exist, one might say that his holy book says that God gave colors and an apple is red, while the other might say that there’s no God and apples are green. They’re both (at least about the color part) right (or wrong depending on how you want to look at it), and objective color still exists regardless of it without the need for any God to have created it. In the same way it’s possible for objective morality to exist without the requirement of a creator, if it is objective it should be demonstrably so, otherwise it’s subjective. In our color example the colorblind people can argue all they want, but if you use an equipment to measure the light waves you’ll have an objective answer for the wavelength of the apple, they might disagree on what that wavelength is (the subjective part) but they agree on the value (the objective part). If something similar could be achieved for morality it would imply the existence of an objective morality (regardless of God) but since we can’t then no objective morality exists.