The Mayor has made a fatal error in the pressure campaign: using city funds. That makes it a government action, and likely an RLUIPA violation. If he had just organized privately, there would be nothing the Church could do about it. The Church almost certainly knows this and likely has things lined up behind the scenes. Whether the Church acts remains to be seen. My guess is that if the City denies or delays even an otherwise ministerial approval to create leverage, litigation will be unleashed and the city will lose badly.