How do you view the question of ultimate authority? And what are the implications concerning other questions of reality? An ultimate authority is an authority that transcends all other authorities and is understood to have legitimate—not arbitrary—rights to govern and rule.
As a Christian, I would argue that God is the ultimate authority of all reality—He created everything and sustains and cares for the world; as humans we were made in His image for His good purposes and are morally accountable to Him; when we humbly live under His legitimate authority—following his design for our lives—we experience joy, harmony with others, flourishing, and knowledge of the truth.
I think there are quite a few implications for how one regards ultimate authority, especially if one embraces a naturalistic (athiest) worldview. We see implications for metaphysics, epistemology, and ethics.
METAPHYSICS: How do I know whether other minds actually exist or if all that I see is an illusion? Without an authoritative voice telling me how reality actually is, no one can know what is real and what is a myth. We are left with skepticism about even basic metaphysical facts: are my senses communicating what is really out there, is my memory reasonably trustworthy or implanted in my brain 5 minutes ago?
EPISTEMOLOGY: In a universe without a personal ultimate authority above, where do the laws of logic come from and how do I know they lead me to real knowledge? In an ‘ultimate authority-free’ reality, why should I be bound to the laws of logic or reason and how do I know they lead me to some kind of truth about reality?
ETHICS: In a world where there is no legitimate authority above humanity telling us how we ought to live, then might makes right. Whoever has the power gets to decide what is right or wrong—in the end, all we have is human preference.