PZ Myers has an excellent bit of creative writing up titled Planet of the Hats that does an excellent job of illustrating religious beliefs.
I know you will not believe me, but I swear it’s true: I’m not of this earth. I fled here years ago because my home planet was driving me crazy. Let me explain.
My home world is very much like this one. It’s populated by billions of bipedal primates, who are just like people here: sometimes foolish, sometimes wise, sometimes hateful, sometimes generous. They are grouped into cities and nations, and sometimes they have wars, and sometimes they cooperate. You really would have a hard time telling our two planets apart, except for one thing.
My people are obsessed with hats. Almost everyone wears them, and a lot of their identity is wrapped up in their particular style. Some people always wear cowboy hats, for instance, and others wear bowlers, and each think the other is exceedingly funny-looking, and would never consider switching. They have elaborate ceremonies for their children in which they confer the hats, and kids often go to special schools once a week where they learn about the history and significance of their hats. Everyone has the importance of hats drilled into them from birth to death.
The particular type of hat was critical. Individuals only rarely changed hat styles, and when they did, it was considered grounds for sorrow by those who wore the abandoned style, and cause for rejoicing by those wearing the newly adopted style. Sometimes people would invent new kinds of hats, which were typically regarded as bizarre when one person was wearing it, but once a sufficient number switched to the new style, they were respected automatically. It meant that streets of our more cosmopolitan cities were filled with strange and comical hats bobbing along, but no one laughed. Laughing at a hat was considered a heinous crime.