The proposal to add an amendment to the United States Constitution is driven by a desire to protect marriage because it is the foundation of society and necessary for its continued existence. Note that I am careful NOT to say marriage is merely the foundation of our society, as if marriage were an American institution. The life of all human society depends on husbands and wives committed to life-long union.
A Constitutional amendment defining marriage appropriately might not be the worst thing to ever happen. However, it would be a violation of the Conservative principles, particularly that of limited government, that have served to make the United States of America history's strongest most prosperous nation and to enable the U.S.A. to export desire for liberty, as well as its reality, around the world.
Conservatives, like Thomas Jefferson, John Adams, James Madison, and others, rightly understood that people can only possess liberty when the government is restricted as our Constitution was designed to do. So-called 'Liberals' disagree. Communists, Atheists, Homosexuals, and others, have repeatedly applied methods to use the government, both in legal and illegal ways, to force tyrannical, unconstitutional policies onto our people.
I'm not at all comfortable with government at any level requiring me to be licensed in order to marry the woman of my dreams. When a marriage covenant is enacted between a man, a woman, and God, an oath has been taken. Two people are married. What has government to do with it? Who is some bureaucrat to tell me, my wife, and my God whether or not we are really married and our vow is legitimate?
It does occur to me that, in its appropriate role to protect us from each other when necessary, some level of government may need to know who is married in order to prevent and/or punish bigamy, for example. But, can you see that allowing marriage to be defined by government gives it too much power over our personal lives?
Because of its profound significance, defense of marriage is not only good, but also necessary! But, like flying planes into buildings full of innocent Muslim civilians in order to defeat Islamic Fascists, to propose a Constitutional amendment defining marriage is to adopt and condone the tactics of the tyrannical homosexual agenda.