Final answer:
The assumption that the existence of God is a basic requirement for any moral system is false. Moral systems can be based on both theistic and non-theistic foundations, and ethical frameworks can provide guidance on behavior without necessarily invoking a divine entity.
Step-by-step explanation:
The statement that a basic assumption of any moral system ought to be the existence of God is false. Moral systems can indeed be based on the concept of the divine, where God is seen as the exemplar for virtues and values or the ultimate judge of right and wrong. However, moral systems do not necessarily require belief in God or any divine entity as their basis. There are ethical frameworks that derive from secular philosophies and reasoning about human affairs, nature, or other non-divine foundations.
Divine and Religious Foundations for Moral Values suggest that what is 'good' is good because God commands it, proposing that morality is based on following God's teachings. However, skepticism about morality and the existence of God, as put forward by philosophers like David Hume and Blaise Pascal, challenges the necessity of God for morality, pointing out that normative claims ('ought' statements) cannot be proven in the same way as descriptive claims ('is' statements), leaving room for the development of moral systems independent of the divine.
Ultimately, moral realism and a moral theory seek to establish frameworks for moral values that can guide behavior logically and consistently. These frameworks can be either theistic or non-theistic, demonstrating that the assumption of God's existence as a foundational requirement for morality is not a universally accepted or necessary principle in the formulation of moral systems.