Let me say this once: I think interracial marriage is morally right. I think anyone should be able to marry anyone no matter what. But Ali, you appear to want someone who does not agree with this for the sake of debate so I will do my best to represent the opposite thought (WARNING: I DO NOT AGREE WITH ANYTHING I AM SAYING). Here's what I found from some research...
Interracial marriage promotes whites and african americans to marry each other, which should not occur. Our founding fathers recognized that there was an obvious difference between the two races and that this should be respected (Yeah, I have no idea why people actually think that's a valid argument...). Furthermore, interracial couples tend to have more domestic violence. This leads to an increase of bad families and tends to make the child lead an unhealthy lifestyle.
If you're religious, the bible doesn't support interracial marriage. The Apostle Paul: Acts 17:24-28:"Thou shalt not take a wife of the daughters of Canaan." Canaanitetes were black people.
Also, itnerracial marriage ruins the identity of a race. By marrying other races, we'll slowly no long have certain races (WTF...)