Diversity is neccessary for the evolution of ideas. By collecting people, you also assemble their religions, gene pools, and their philosophies.

"Common sense is the collection of prejudices acquired by age eighteen."

-Albert Einstein (1879-1955)

What you deem as common sense, someone else will see differently. By embracing the beliefs of others, you will in turn gain wisdom, that in the future will make it possible for you to form your own beliefs. By embracing others, you gain new perspectives, and can see problems you couldn't before (Part of the idea behind Open Source). By embracing others, you learn to resolve differences, and solve problems better.