This framework for analysis helps to explain why the two opposing sides in this controversy see the issue in such starkly different terms.

Those opposed to same-sex marriage see marriage as an essentially heterosexual institution that is fundamental to human happiness and the well-being of civilization.  Those who support same-sex marriage see limiting marriage to heterosexuals as a way of exercising patriarchal oppression against sexual minorities.  Marriage is seen, therefore, as an obstacle to human happiness and autonomy that must be either destroyed or radically revised.  The quest for this radical revision is seen as an act of human liberation.  To the conservative, this is a mortal blow directed at the very heart of the culture.

Moral conservatives see homosexual behaviors as matters of grave moral concern.  Moral liberals and libertarians see homosexuality as no more morally significant than the color of one's eyes.  It's just part of what makes some people who they are.

Adding credence to Sowell's argument, a person's position on same-sex marriage is a very good predictor of positions held on other issues as well.  Careful observers know that this is no coincidence.  A cadre of liberal Hollywood celebrities supports same-sex marriage as what they call a civil rights issue and recently held fundraisers that produced millions of dollars to defeat Proposition 8.  Meanwhile, opposition to same-sex marriage is most discernable among conservative Christians and other conservative groups like the Mormons.

The middle ground is fast disappearing, even as arguments based in a framework of natural law seem to carry no public force.  This leaves conservative Christians -- evangelicals in the main -- as the bulwark of opposition to same-sex marriage.  For evangelicals, the question is always a question of what the Bible teaches, and the Bible straightforwardly presents homosexual behaviors as immoral and sinful -- and in stark terms.

Believers committed to biblical authority will find no way to avoid this controversy, and no ground for accepting the "fairness" argument.  If the Bible is the revealed Word of God, then we know that homosexuality is a sin of great spiritual consequence.  Those who reject the authority of the Bible will, in the end, likely come to accept some argument for the normalization of homosexuality and homosexual relationships.

Despite their massive and contentious collision over this great question, the two opposing sides in this controversy are agreed on one major point -- the importance of the issue.  Both sides believe that the victory of their position on this issue is a precondition for true human happiness and human thriving.  And, truth be known, both sides see the other camp as a threat to human happiness and well-being.

To a significant degree, these opposing camps define almost all of reality in starkly different terms.  Both sides bring energy and passion to the public square.  Both sides see the controversy as a battle for the future of civilization.

On that point, at least, both sides are right.