Homogeneity, homophilia and ethnically-specific churches

This continues my series on immigrant ministry.

* * * * *

Pragmatically, the homogenous unit principle would encourage ethnically-specific churches. In 1970, Donald McGavran stated that people “like to become Christians without crossing racial, linguistic, or class barriers”, [Donald A. McGavran, Understanding Church Growth, (Fully Revised) (Grand Rapids: Eerdmans, 1980 [1970]): 223] and cited research that 60-90% of converts were brought to church by a friend or relative [McGavran: 225].
Not much has changed: in 2008, Edwards noted that the “homophily principle”, which “says that people like to hang out with others who are like them”, has often been used to explain the success of homogenous churches, because “people are recruited into voluntary organizations through social networks made up of people who are similar to them.” [Korie L. Edwards, The Elusive Dream: The Power of Race in Interracial Churches (New York: Oxford University Press, 2008): 118].

But this homophilia could lead to an inward turn, a complacency, because we are amongst people who are 'just like us'. This is not unique to ethnic churches - homophilia is broader than ethnicity. People could be happy merely becuase they're with people of their own profession, or social status, or whatever. We must be wary of the 'comfort zone', which could turn our church into a mere social club.

The question is: what are the warning signs that this is happening? I can think of one: a loss of interest in evanglism. Anyone got any others? Also, if this complacency is setting in, what do we do about it?