Teaching the principle of equality is excellent and if it works it will solve the problems with each type, but this approach alone is insufficient. It's not enough to just urge people to think of everyone equally. People need to be educated on what true equality means in each situation. The current state of being is that different types of minorities face different challenges. If everyone born after the year N magically believes what is actually good and right (which is an extremely tall order for any value of N in the near future), there are still a bunch of people alive now who will face some sort of badness as a result of people who don't already believe in equality (or on some occasions, from those who do, but who unknowingly act in a way that doesn't further equality.) These issues are different for different groups, and although there is a great deal of interconnection (which is why you'll often see, for example, anti-racism discussion in a feminist forum), there are some issues inherently related to one particular aspect of minority. For example, if you're pregnant and have to deal with any of the myriad issues springing off of pregnancy, it's because you're female, not because you're black or because you're a lesbian or what have you. (I'd be pretty impressed if someone can come up with a story about someone who is pregnant because they are a lesbian...)