Religion (noun)

1. A set of beliefs concerning the cause, nature, and purpose of the universe, often involving devotional and ritual observances and a moral code.
2. A particular system of faith and worship.
3. The state of a religious.
4. The service and worship of God or the supernatural.
5. A pursuit or interest to which someone ascribes supreme importance.

Origin:

From middle english religioun, from old french religion, from latin religiō ("respect for what is sacred, piety"), from religō ("bind, connect"), from re- + ligō ("bind, connec.t")

Examples:

1. He's studying the religion of ancient Egypt.
2. She's practicing the religion of Buddhism.
3. He's a devout follower of his religion.
4. The church is a place of religion.
5. He's making money his religion.