But don’t you think it a bit odd that a Muslim could be in the line of succession, or a Hindu, or a Buddhist, but not a Catholic?
That's exactly right. That law in England dating back to 1701 does not require a member of the royal family in the line of succession to be an Anglican -- it prohibits them from being a Catholic.
It seems to me that a nation where Osama bin Laden could be king -- but any Catholic cannot -- isn't long for this world.
The king or queen of England is always a Protestant, an Anglican