Internal cohesion should not be confused with harmony.
Ethnically cohesive subgroups or religious sub groups can live in harmony with each other in a larger community without necessarily integrating into a cohesive whole.
The main reason why ethnically and religiously diverse populations do not easily integrate with each other is because the members of such groups focus on what is different—their ethnicity and their beliefs, rather than what is common—their humanity and their values.
Consequently, members of ethnic and religious subgroups who have not fulfilled their deficiency needs tend to congregate together in the same subdivisions for collective safety and support.
Only in highly democratised nations, that encourage individuality, and actively promote equality, will you find people of different ethnicities or religious affiliations living alongside each other on the same street. They are able to do this because they have individuated, and in so doing, they have traded their kinship bonds for value bonds. They have learned to identify themselves in a larger way—with their larger community or their nation, rather than their ethnicity or religious affiliation.
The following table shows the Seven Levels of Identity. (Click on table to enlarge)
True internal cohesion can only occur in ethnically or religiously diverse groups where people are encouraged to individuate and self-actualize. Only when people feel free to choose their beliefs and their values can they come together to form internally cohesive communities or nations built around shared values and common goals.