How do we celebrate diversity? By not celebrating it. It's our family philosophy that nobody is the same, and that's what makes people interesting. Without differences there would be no reason to leave the house! We try to meet new people every place we go, and to learn about their lives by asking questions and really listening to their answers. In addition to the "get out and talk to people" plan, we read all kinds of books. Literature is an invitation to enter someone else's mind at a depth rarely achieved in everyday interactions.
The other, harder, aspect of embracing diversity is in accepting differences that are in conflict with my lifestyle and beliefs. Each day I am reminding myself to exercise compassion toward those with whom I disagree. Instead of mocking those with other ideas, or getting upset about the causes they promote, I try to be grateful for the reminder to teach Lucy about what I believe. Instead of stewing about other's actions or beliefs, I try to find solutions to the problems they think they are correcting. (In the first draft of this post, I mentioned an organization by name. Much work to do here.)
What is the best way to teach appreciation of differences and compassion? I think it has to be by example. Lessons and discussion are valuable, but can never surpass simply setting principles, and working daily together to uphold them. It's hard work, but the reward of approaching others with an open mind and heart and receiving responses in kind is well worth the effort.