One of my favorite bands (Tony Raburn's definite favorite) is Rush. One of their songs, "Subdivisions," talks about how much peer pressure is a part of life. Conform and be cool or be cast out, they sing. The world certainly works that way. I went to high school in coastal Georgia, a very large school in a military town. Did we ever have "groups." We had goths, headbangers, preps, jocks, rednecks, geeks, and a large number of ethnic groups. While some were harder to pigeon hole and felt at home in multiple groups, there was much "subdivision" in the high school halls and shopping malls. The worldly way of thinking is to divide, group, alienate, and pit one against another.
Through the cross, Jesus died to eliminate enmity and division. Jews and Gentiles were divided, but the cross was God's tool of reconciling them back together. This place of unity is called the "one body" (Eph. 2:16). That "one body" is identified as the church (Eph. 1:22-23). This means that God designated a place where subdivisions do not belong. The church is to be a people who are united (Eph. 4:1ff). We come into Christ from so many different places. Perhaps we were goths, headbangers, preps, et al, but when we come into Christ we are one body. This can be uncomfortable and unnatural, but it is what sets apart God's "set apart" from those who conform to the world. In Christ, we are transformed (cf. Rom. 12:2). Our effort is to be toward oneness. It must be to eliminate all barriers, race, education, income, background, and whatever other distinctions the world is prone to make.
It is one of the great blessings of Christianity! Let the world prejudge, make distinctions, and isolate. The church is to be a welcoming, loving, and uniting group! May this ever be our focus and desire. Jesus was willing to die for that ideal (cf. John 17:20-21).