How do you have unity and diversity at the same time?
People can be united, or they can be diverse, but they can't be both at the same time.
Come check out the addled people who say such things - you'll see that many of them also believe gay couples who adopt are families, vicious killers don't deserve capital punishment and anti-Americanism is patriotic. That's just the ones who aren't smoking dope.
They'll also enjoy twice as much press as we will while the police will be facing them, not us.
Different types of people can be united for a cause, so you can have unity and diversity at the same time. You can't have unity AND division, which is probably what you were thinking.