Found this cartoon by Kevin Siers of the Charlotte Observer somewhere in my internet travels a few days ago and, as a mixed-race gay man, I have to say that the message is powerful and absolutely right on.
Keep in mind that the arguments against gay marriage that are making the rounds today are the same arguments (from the same kinds of people) that they used to try to justify preventing people of different races from marrying only a few decades ago (Loving v. Virginia (1967)).
