The issue of ethnicity is an interesting one. My pastor is from the United States but he married a woman from Italy. Both of them are white. Now tell me, did he commit sin by marrying someone of another ethnicity despite both of them being white?
If we are all truly descendants of Adam and/or Noah, then we are all of the same race.
race: a family, tribe, people, or nation belonging to the same stock.
stock: the descendants of one individual.
However, as we can see clearly, in this world we draw different boundaries with regard to the term race, whether we do so rightfully on not. While it seems that these boundaries are changing to some extent, they still exist to a great degree.
The Arabic peoples all have one common ancestor that is not shared by the Oriental peoples. And the Oriental peoples have one common ancestor that is not shared by the Caucasian peoples. Therefore, by the same definitions of race and stock, we can see that we are not just one race of people, we are also many races of people throughout the world.
We could even extrapolate this further and say that every single person alive is the stock of a new race of people.
Thus, it cannot be said that interracial marriage itself is a sin, unless of course procreation itself is a sin, which I highly doubt.
Therefore if it is a sin for one person to marry another person, we're going to have to look beyond race to each particular marriage union, and the cultural, religious and ethnic differences that exist between those individuals that marry, as well the particular dispositions, attitudes, beliefs, and thoughts of the individuals being married. And of course we need to focus our attention on those marriages which include at least one Bible believing person. If you do not believe in God, or the Bible, then there is really no point in discussing sinful marriages to begin with.
The racial boundaries that human beings have set, whether rightfully or wrongfully, are a result of apparent differences in skin color. However, it is not the differences in the color of one's skin which determines whether one particular marriage is sinful or not. It just so happens that cultural differences, religious differences, and ethnic differences, and even various stereotypical prejudices, have been associated with skin color. But differences in skin color itself cannot be a determining factor to determine if a marriage is sinful.
ShadowWolf, in post 3 brings up this point, "Many people do mention the kids, and unfortunately society has made it very rigid and sometimes difficult for biracial children"
So here we see that a biracial child often faces hardship because their parents chose to be married. I have to ask, why did these parents not consider their children before they got married? Were they being selfish? Were they trying to reform the world view despite the well being of their child? Was it neglect and ignorance? Didn't they care about the consequence to their children? Are they sacrificing their children for the betterment of mankind? I don't know. But it is quite clear to me that such a marriage could been sinful.