I think either you missed my point or you failed to think it through. Again, your reasoning boils down to "Empiricism tells us racism is false", and you are relieved that this is the case. You also say some ignorant things about the very concept of Utopia (the very idea of utopia is precisely that it is unattainable by design, but nevertheless you strive for it. To say that utopia is never reachable isn't exactly an intelligent criticism of it).
What you fail to grasp is that by reasoning in this manner, you fall prey to the scientific contingencies of each era. To say that we have no empirical evidence for genetic differences in humans is ignorant itself. There have been a lot of tentative hypothesis and many correlation studies that claim that this is in fact the case ("The Bell Curve" as a recent example of this), but the people who try to porsue or develop this kind of reasoning are usually shunned for racist ideas (and I think this shunning exercise, while slightly anti-scientific, is healthy in a sense). It is also a dead give away: If the scientific evidence was actually undeniably giving us the idea that we have indeed genetic differences that make a certain color more this or that or the other, then I am left with the idea that you would be a racist, for that would be where the evidence was driving you.
But the problem of racism isn't empirical, isn't about facts. It's about values. And values, however informed by facts, are never derived from facts. They are always derived from other values. This is why utopia is valuable: it is about the world you want to live in, not the world where you live in. This is why the fight against racism is an idealistic struggle, not a scientific one.
Another example: egalitarianism. Egalitarianism is, empirically speaking, an absurdity. People are different, period. But the ideal of egalitarianism is not about possibilities or facts or physics or whatever. It's about an utopian drive ideal that guides our values towards the society we want to live in. (These ideals are always brought down by facts and brute physics, etc., but that's a given).