Thresholds—doorsteps—are sacred. Neither inside nor out, both inside and out, the threshold is, like all other betwixt-and-between places (and times), a major locus of sanctity in any building.
In Old Craft lore, the Horned, preeminently god of the In-Between, is said to be seated on every threshold. Every passage through that doorway is (or at least has the potential to be) thereby a rite, an encounter with a god.
For this reason, they say, it's best not to tread directly onto a threshold; one should step over it instead. (It's old woodsman's lore never to step on anything you can step over.)
This is really a pretty subversive idea. Every building contains within its very fabric a place inherently sacred to Old Hornie: your house, the supermarket, the mall. Every building makes a place for Him. So there's a place sacred to the god of the witches in every synagogue, church, and mosque on the planet. Now that is subversive.