While Deism limited God, Naturalism eliminated God altogether. Naturalism asserts that matter exists eternally and is all there is. God does not exist. The universe is a closed system. The idea of human dignity derives from the evolutionary necessity of survival of our species.
Death is the extinction of the individual.
Human history is a linear system of events linked by cause and effect without any overarching purpose. Morality is ultimately decided by human beings and is relative, depending upon the survival needs of the individual and the human species. Strictly speaking Nihilism is not a philosophy but a denial of philosophy, a denial of the possibility of knowing, a denial that anything is valuable or meaningful. Interestingly, Nihilism is the logical conclusion of Naturalism. It is a philosophy of despair and is unlivable.