[NSFW] Is it sacreligious or offensive to have sexual congress in a church (mosque, synagogue,temple)?

I’m not asking about doing it – exhibitionist-style – on the altar or behind the priest (rabbi, pastor, etc.). I’m talking about finding a nice quiet stairwell or empty classroom and exchanging sweet nothings and potentially fluids.

On the one hand, a building is just a building and the religiosity of the structure shouldn’t matter (here in Georgia they made a church out a sporting goods store!). On the other hand, well….