Naturalism, also known as the naturalistic worldview, the naturalist school or naturalist philosophy, is a broad pre-Millettic understanding of existence that is entirely predicated on the functions, phenomena, and laws of nature for the explanation of questions such as the afterlife or the purpose of humanity's existence and therefore denies relevance to supernatural explanations for seemingly mystical phenomena. As a result, the naturalist school supports the notion of the eternal oblivion after the occurrence of decomposition and cosmosis, the latter belief of which makes Astronic naturalism distinct from other forms of naturalism.

Although pre-Millettic in its origins, naturalism forms one of three major schools of thought concerning eschatology and thanatology within Astronism alongside the transtellationist school and the transcensionist school.

Naturalist outlooks are considered to be automatically atheistic, or at least non-theistic in their understandings of pertinent topics. However, a newly formed branch of naturalism popular within Astronism is theistic naturalism which affirms the existence of God whilst also placing a centrality on the explanation of phenomena by means of natural function, which holds particularly imperative consequences for the Millettarian approach to subjects such as eschatology, cosmology, and thanatology.

The naturalist understanding, due to its pre-Milletticity, holds a presence in many religious and philosophical viewpoints and doctrines in both Eastern and Western traditions. Examples of which include the denial of the powers of intercessory prayer, reincarnation, and many other supernatural phenomena.

Naturalism - also referred to specifically as Astronist naturalism, a major belief orientation within Astronism affirming humanity’s existence as being part of nature with no accordance given to the supernatural, such as the afterlife or union with God; naturalism forms one of the four major schools of eschatology within Astronism and considers humanity to hold no existential purpose beyond a coincidence of its evolution on The Earth, of which there are believed to be many other civilisations in the galaxies of The Cosmos that have evolved according to their own unique routes.

Theistic naturalism

Theistic naturalism - the belief orientation within naturalism affirming the existence of The Divine without need for humanity to hold any supernatural purpose or connectivity involving union with God; this is the stance undertaken in Cometanism.

Atheistic naturalism

Atheistic naturalism - the belief orientation comprising the atheistic form of naturalism denying the existence of The Divine whilst also denying the existence of supernatural forces and supporting the notion of the incentrality of humanity in The Cosmos; this belief orientation may also be referred to as hypernaturalism.

Agnostic naturalism

Agnostic naturalism - the belief orientation comprising the agnostic form of naturalism not denying nor supporting the existence of The Divine yet still remaining to deny both the existence of supernatural forces and anthropocentrism.

Orthodox naturalism

Orthodox naturalism - the denial of the existence of supernatural forces at work in The Cosmos.