Cleanliness was a virtue. They told him that.
"Who are they?" The others would ask. The others didn't believe in they. But they are there. They must be. Or else, why they tell him that?
They also told him of the magical properties of the string. The others didn't believe in the string, but he convinced them.
you must try the ritual of the string, or it will not work it is powered by nonbelievers
The others were intrigued. Still, they did not believe, but, perhaps, what harm is it to see where this leads?
Of course, the ritual of the string begat the ceremony of the toilet paper, the event of the doorbell, and the celebration of the vacuum cleaner.
Eventually the others learned and they no longer participated. No answers were even given to their queries. He still believed though. And his one man religion continued. He worshiped the only gods he knew. He spent his life trying to convert, but no man would listen.
When the others went away, he felt lonely. For his gods were powered by the non-believers.
But forever, he remained clean.