Naturalism is the philosophical position that sense can be made out of the world and reality, without reference to supernatural entities such as God. It is now the defining essence of science, and where a few hundred years ago scientists were unafraid of invoking God as a final explanation. Now even the origin of matter and energy are thought to be naturalistically explicable, and there is no need for the God hypothesis. Look how smart humans are!
However, that all assumes that the science is correct, and I have my doubts, as do others about all aspects of this, something I cover in my iconoclastic posts here. For example, how can science claim to the explanation of all reality, within the language of mathematics, when at the foundations of logic, there are unsolved, maybe unsolvable logic-semantical paradoxes, reducing everything to inconsistency, such as Curry’s paradox, where everything can be proven: