This is a dispute about cultural supremacy. That’s why the last, most bitter holdouts against gay marriage are the same institutions, people and states who were the last bitter holdouts against the Civil Rights movement.
Gay marriage is likely to destroy something, but it’s not marriage. The fight over gay marriage is going to severely damage the lingering cultural supremacy once enjoyed by white Protestants.
We are on the cusp of experiencing real pluralism for the first time in the country. That’s why same sex marriage matters and that’s why the battle lines are drawn across the same boundaries as in the Civil Rights movement.