Homosexuality is sinful behavior. In the bible it is described as an abomination. Homosexuals undermine society and erode moral values. It is a lifestyle that is both physically and spiritually unhealthy.
“No successful civilization in the history of the world has endorsed homosexuality.” -2010
“No successful civilization in the history of the world has endorsed the concept of a round earth.” -1491
I don’t think a Biblical argument is neccessarily a good argument when it comes to constitutional rights. A better argument is the one Michael Medved uses which is the fact that homosexuals aren’t barred from getting married whatsoever. They may marry one person of the opposite sex who is of age, just like anyone else can. The real question is where we draw the line of regulating marriage. Homosexuals seek to draw it in a different place, problem is if we do that, where does it stop. Even their own “marriages” will become meaningless at some point.