A number of people believe that it's the will of a divine being that sets the foundation for what is ethical and what's not and that this divine being is the ultimate authority on it. Not only do I disagree with the Divine Command Theory but I find it fallacious and potentially dangerous as well as scary.
I agree that Moral Universalism (Not to be confused with absolutism or relativism) can and does exist regardless of whether you are atheist, agnostic or religious or other differentiating features. I also like to think of Moral Universalism somewhat akin to a "common sense morality" shared by millions of us all across the globe.
Now one of the refutations of the Divine Command Theory is that certain moral codes we see all over the globe today existed long before the idea of any Deity was even conceived of as seen in also other religions and philosophies that don't worship a Deity such as Buddhism, Jainism, Taoism, Confuciousism and so forth.
Moral Universalism does exist and it is inherent in our biology. As the Dalai Lama said, "Unless we have some kind of mental dysfunction we all share the desire to be happy and for no harm to come our way." This is also true from a scientific standpoint. Also from a Science point of view, most of us have a thing such empathy and compassion among other useful emotions that are at the root of us not causing harm to other beings.
Albeit scientists have come up with research about as to why in some cases the harming of others may affect our survival and because of that's it's best not to do so this still does not exclude the general foundational basis for universal morality inherent in our biological makeup. Nor does this lead to the conclusion that a Divine Authority sets the foundation of what's ethical and what's not as that would not follow logically from the premise.
So in conclusion Moral Universalism is something that exists that is devoid of any Divine Being and is also regardless of whether one is religious, atheist or agnostic. Simply speaking, all that's a need for this universal morality is to be human with the desire to not be harmed and an emotional as well as rational understanding as to why we shouldn't cause harm to others; this is what sets the foundation for universal morality; other ascriptions need not apply.