The homogeneous unit principle is one of the most controversial issues in mission thinking. It was originally described by Donald A. McGavran in Understanding Church Growth (Revised Edition, Eerdmans, 1990).
McGavran suggested that for mission and evangelism to be most effective, people need to hear the gospel in their language and see it lived within their culture. It is positively healthy for churches to appeal to people of a similar culture – from youth congregations, to churches for specific ethnic groups to churches for deaf people.
Critics complain that this is a betrayal of the reconciliation which lies at the heart of the gospel. Christ breaks down every dividing wall, making humanity one (Ephesians 2.11-22). Church should reflect this. 'Niche church' panders to a consumerist rather than a kingdom worldview. However, several theological themes support the homogeneous unit principle.
Creation
Cultural diversity can be seen as part of the diversity built into creation and as essential to being human. Genesis 10, for example, describes how humankind split into clans and nations as it multiplied.
Though Genesis 11 associates the emergence of different languages – a key aspect of cultural diversity – with human pride, these differences are viewed more positively in Acts 2. The Spirit enabled each language group in Jerusalem to understand the apostles.
God's solution to the linguistic chaos in Genesis 11 was not to obliterate language differences, but to allow communication across them. Reconciliation requires the ability to transcend cultural differences, not to remove those differences.
Accordingly, in Revelation 21.24 and 26 every tribe and nation is gathered in the new Jerusalem, preserved in its cultural identity (homogeneous) while being perfectly at one with each other (heterogeneous). The implication is that the renewal of creation will bring diverse cultures together without destroying them.
The incarnation
Jesus took on the culture of those he was called to reach. He became a Jew in order to reach the Jews. St Paul echoed this when he wrote, 'To those outside the law I became as one outside the law… To the weak I became weak… I have become all things to all people, that I might by all means save some' (1 Corinthians 9.21-22).
A church needs to be immersed in a specific culture to serve that culture. Otherwise it will seem alien and separate. People will be unable to identify with it.
Reconciliation
Reconciliation won't be achieved by mixing different cultures together. At best, all you would get is a new subculture as the group developed its own distinctive patterns of behaviour. To develop its identity, each group of mixed-up cultures would evolve its own style, which would be different to other groups. These differences would risk becoming new sources of division!
Being church in different ways at different times and places, and in different sized groupings, will allow variations in culture and theology to exist. Unity can be expressed by joining these different forms of church together – for example by:
- eating and having fun together.
- working together in mission.
- communicating with each other.
- supporting one another in prayer.
- occasionally worshipping together.
A key part of the church's mission is to join the cultural fragments of society, so that it can begin to join those fragments up.
Social justice
The gospel lifts up the poor and the marginalised. But when you mix up two cultures in the interests of reconciliation, the more powerful one dominates the weaker.
Just because you mix two cultures doesn't mean that you get two equal cultures. One usually has greater influence than the other. The dominant culture is not necessarily the one with most people. It tends to be the culture that is more wealthy and better educated.
To be good news for the poor, there must be expressions of church not just for the poor, but of the poor and in their culture (and of the deaf, the gypsies, the addicts…). Otherwise groups on the edge risk being marginalised yet again.