Also all the insulting shows that the possible vision of 'marriage as a social institution' has not entered into their heads.

The example of 'property' is good because it is also a social institution and it is something which one cannot take for granted (there are societies ---hippies--- which deny the existence of it). When some minority claims their right to property (for example, the 'poor') or claim that the 'right to property' is harming them, what shall we do?

Are we bigots because we insist on the right to 'property'?