Because "marriage" is not defined as the union of same sex. It is a traditional religious custom, ordained by the church as a union between man and woman for the purpose of procreation and family. It is consequently sanctioned by the state, but it is a fundamental tradition and religious custom, and a fundamental part of religious faith in this country.
Let me attempt another absurd analogy here, since you love those so much... and let me first say, it is difficult to come up with any analogy to illustrate the point, because nothing else in our society can relate to this... but... imagine if you will, a movement became widespread to abolish operating motor vehicles on Sundays. Global Warming, Cost of Gas... whatever the reason, Sunday is targeted because it is the least 'productive' day of the week for most Americans. It is estimated we can save billions each week and help the environment to abolish driving on Sundays... well, Sunday is the traditional day for most all religious worship services. No exception is going to be allowed for the churchgoers, they will just have to walk to church or something... tough shit. Is that right? What if churches banned together and bought electric shuttle buses to transport their parishioners to and from services, and the 'ban Sunday driving' advocates included electric vehicles in their initiative, citing it wouldn't be fair to allow any type of vehicle on the road on Sunday... In fact, you can't even come out of your house on Sunday! Is that okay? You see, it is a direct assault on the religious practice of Sunday worship, even though good reasons and excuses can be found for doing it. Or what if there was a movement to make all people work on Sunday, prohibiting them from being able to attend church services? What if we redefined "prayer" to include paying homage to homosexuals, and made this mandatory on Sunday? Could this be a fair thing for government to do, one that is mandated to protect the freedom of religion? I think not!
The issue here is, the religious institution of marriage and what it means to those who are devoutly faithful to their religious beliefs. As a society that protects religious freedoms, we should be sensitive to those beliefs, we shouldn't pass laws which destroy those beliefs or attack the religious traditions. That is what is being done with 'gay marriage' exactly. As you have demonstrated, it's not about your love of gay people, it's about your hate of religious people. That is why I am opposed to Gay Marriage, and always will be! The problem can be solved without encroaching on the religious sanctity of marriage, and that is what SHOULD be done in this case.
