Astronism, also known as the religion of the stars, is an Astronic cosmocentric organised philosophy that is based on the fundamental principle that faith, the meaning of life and emotions traditionally associated with religious ideas like god(s), the afterlife or a spirit realm can equally be obtained from "the stars" or The Cosmos as a whole, animistic conception of outer space. The beliefs and practices of Astronism act as complimentary tools that a person may use to improve their intellectual, spiritual, philosophical and physical proximity to and understanding of The Cosmos.

Despite being grounded in this notion of "astrospirituality", Astronism is mainly a naturalistic belief system which has garnered it a considerable atheist or otherwise  irreligious following. Although it consists of a developed theology, Astronism remains firmly cosmocentric and by subsequence, is therefore largely non-theistic whereby the question of the existence or non-existence of a creator god is peripheral to the belief structure. Therefore, followers of Astronism, known as Astronists (collectively known as the Astrosa), profess a variety of theological positions which shapes the approach they take in engaging with Astronist beliefs and practices.

Astronism was founded by the philosopher Cometan in history's longest religious treatise called the Omnidoxy which, upon completion, extended to over 2 million words in total length. Considered a synthesis of religion and philosophy, Astronism emerged from Cometan's development of a new branch of philosophy called cosmontology which studies explores space exploration, astronomy, and questions regarding the nature, structure, purpose, and eventuality of The Cosmos.

Astronism is predicated upon the belief in a process called cosmosis which involves at least a physical if not also a spiritual union with The Cosmos upon one's death. Cosmosis is achieved by all animate beings while its counterpart belief known as astrosis states that cosmosis is achievable before a person dies. Astrosis involves a physical, spiritual, intellectual, religious, and philosophical union with The Cosmos through a series of practices, beliefs and principles emanating from within Astronism.

It is the goal of all Astronists to experience this process of astrosis. Three schools of thought of Cometanic origin emerged regarding cosmosis including transtellationism, naturalism, and transcensionism. Each of these schools holds a variety of beliefs and opinions regarding the nature, purpose, form, and function of cosmosis with the latter two schools expressing a naturalistic approach while the former involves supernatural beliefs.

Astronism is classified as part of the Astronic tradition of religions that traces its lineage back to the astronomical religions practiced during the Upper Palaeolithic period of the Stone Age some 40,000 years ago. Astronism's theological orientation is primarily panentheistic and deistic, but to describe the concept of The Divine in Astronism, the term depadotheism is often used which is a term of Cometanic origin.