Do you find yourself liking someone because they agree with you or see things in a similar fashion to how you see things?
Do you also find yourself disliking someone because they disagree or are on the opposite end of your point of view?
Since we see across the globe a variety of opinions, points of view, beliefs, historical narratives, ideas and so on, do you think it was God's purpose to create a cloning of mankind? Don't we see human beings with various traditions, cultural constructs, societal taboos and different laws? If one believes in an all knowing God, surely He has either allowed or planned the world in this way!
We see variety in nature within species of animals, plants, landscapes, etc.
We also see singularity and oneness in all of creation and in ourselves, can't we? Despite the external differences, we can appreciate our sometimes unnoticed commonality. We sometimes have to suspend the obvious differences to see clearly the likeness. We have to sometimes suspend how the media portrays people of other cultural and religious backgrounds to see their humanity and how it complements and, at times, equates ours! We have to sometimes consider others better than ourselves in order to keep ourselves from believing 'our' mind's view is more accurate than theirs. It is this very simple and universal consideration which is capable of preventing needless wars and ignorant division.
Hasn't all of mankind been separated by time and geography? The archeologist and historian can agree that as peoples moved away from one another, their original thought processes changed and evolved according to exterior factors. Eventually, new opinions were formed. The closeness that the direction the world is headed in is one to be embraced, otherwise the inner likeness can be overshadowed by the exterior difference.