Coreligionist (noun)

1. A person who belongs to the same religion as another.
2. A person who has the same religious beliefs as another person or group.

Origin:

From the word "co" meaning "together" and "religion" meaning "a set of beliefs concerning the cause, nature, and purpose of the universe" and "ist" which is a suffix indicating a person who practices or is an expert in a certain activity.

Examples:

1. He was a coreligionist of mine, and we often talked about our shared beliefs.
2. She was a coreligionist of the group and always attended their religious ceremonies.
3. He was a coreligionist of the temple, and regularly participated in the religious services.
4. She was a coreligionist of the mosque and always supported the community.
5. He was a coreligionist of the church and always showed his support for the pastor.