Externalism and internalism in religion is an Astronist theory on the philosophy of religion that directly emerged from the comparison of Quakerism with Astronism and the realisation that these different religions hold markedly different views on where the source of spirituality and existentiality comes from. Externalism is, therefore, representing religions which profess that something or somebody external to the self is the source of one's spirituality while internalism emphasises that the source of one's spirituality and existentiality comes from within oneself without need for the external world. 

Astronism is classified as an externalistic religion due to its basis on the fundamental principle that spirituality and existential purpose is derived from space, astronomy, and humanity's exploration of The Cosmos as certainly external to the self. In fact, in Astronism, particularly in the transcensionist school of thought, the self plays a minor role in comparison to the collective self of humanity. Despite this, a person is free to approach Astronism from an internalistic perspective, however, the technicalities and resulting philosophical view of what an internalistic approach to Astronism would look like remains questionable as it has not yet been widely recorded. 

List of religions considered internalistic:

• Buddhism
• Jainism
• Quakerism

List of religions considered externalistic:

• Astronism
• Christianity
• Confucianism
• Islam
• Hinduism
• Judaism
• Shenism
• Shinto
• Sikhism
• Taoism