My understanding is that: (a) the three big Abrahamic religions all place the most emphasis on worshiping as a congregation on different days and (b) among each group, a minority of people who identify with the label actually go to worship with a congregation regularly. Would it really be _so_ bad if you had one big fancy palace which switched from hosting Muslims on Friday, Jews on Saturday, Christians on Sunday and could be a museum / community space / charity space Mon-Thurs?