noun
religion; religious affiliation; faith; creed
Broad noun for religion as a system of belief, a person's religious affiliation, or a faith tradition; context decides whether English uses 'religion,' 'faith,' or 'belief.'
彼は特定の宗教を持っていない。
He does not have any particular religion.
宗教
Freedom of religion is guaranteed by the constitution.
noun
religious activity; religious practice
Refers to religion as an area of practice or activity, often made explicit in phrases such as 宗教活動; as a standalone noun it can overlap with the general sense 'religion.'
その団体は海外でも宗教活動を行っている。
The organization also carries out religious activities overseas.
彼女は若いころから宗教に身をささげてきた。
She has devoted herself to religious life since she was young.