My simple answer? Do not acknowledge race, gender, sexual preference, religion, nationality etc... AT ALL! No forms should include sections for race, gender, religion, etc... If we are all equal, than all of those are irrelevant, so there's no need to track it. Also, no special holidays. There's no such thing as "XXX" history. There is only HUMAN HISTORY.
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Everyone should be regarded solely through their own merits, not through happenstance of birth or genetics. We don't celebrate hair colors or foot sizes, so why celebrate any other genetic irrelevance like race, gender or color? Those aren't accomplishments, they're just random variables at birth, much like eye color.
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In short, treat everyone the same, and stop focusing on our differences. No more "strength through diversity" campaigns. Let's start having "strength through competence" campaigns.