Redefining marriage?

Opponents of equal marriage rights are ever more desperate for arguments. A currently popular one holds that government should not use its coercive powers to redefine the word "marriage." Am I allowed to have multiple wives and concubines? Does a wife lose her legal identity upon marriage? No? Then it looks as though marriage has already been redefined. Also, it makes no sense to argue that while the word "marriage" is sacred, government has free rein to redefine the word "equal," as in "equal protection of the laws," however it sees fit.

In short, the only way to keep government from redefining marriage is to keep government from defining marriage at all. I believe that that course of action would be ideal, but, as I have said before, I do not want the perfect that is a long way off to be the enemy of the good that is coming to pass.