Why wouldn't surrendering the church be an option? Lou had no particular attachment to the building, and clearly even those who did, like the presumably-Christian caretaker, didn't feel strongly enough about it to risk their necks. A Sphinx in the church couldn't possibly be the cause of the fog (particularly if she had just arrived this morning), so what did it have to do with them? This sounded like a problem for the Ministry — once magic had been restored. Were they really considering risking their lives on how well a group of random strangers could solve a riddle?

He shifted his weight from foot to foot, obviously uncomfortable with the proposition but unwilling to be the first to vocalize his objection.