Given that this is something people frequently feel strongly about, there are important subcategories. "Not religious" can mean passive/apathetic ("don't care"

Given that this is something people frequently feel strongly about, there are important subcategories. "Not religious" can mean passive/apathetic ("don't care"), or active/idealogical ("There IS no god!") One can be mildly or very religious without following any rituals or having anything to attend Spiritual may or may not fit into any category because of the vague allusion to "Standard Definition". This may imply author only means large historical/traditional/formalized religions (in which case "Spiritual" or "New Age" would go into Not religious"), or religion is meant to be encompassing and inclusive (in which case they would fit into one of the other categories).