Yes, Churches- all churches/places of worship- should be taxed.
If they can afford to build extravagant buildings, they can afford to pay taxes. I understand the need for a large building to fit the congregation, but does it need to be a multi-million dollar building like some churches? Does it need stained glass windows? Do you need a separate dining hall/rec hall? No, you don't. You need an altar, a roof, a few windows (of the pane/sheet glass variety), pews, rugs (in the case of Islam), and I'm not sure what goes into a Jewish Temple.