James McGrath asks this question on his blog: how diverse can a church be? I think there are couple of ways of thinking about an answer. One is that it depends a lot on the emotional health an intelligence of the people in leadership at the church. Emotionally healthy people have clearly self-defined values and boundaries and are not threatened by people who have different beliefs. If the leadership is healthy they can model healthy dialogue and conflict and the congregation can tolerate, perhaps even welcome, a certain amount of diversity. On the other hand if the leadership isn't emotionally healthy then they will probably be threatened by diversity and seek to enforce adherence to a more narrow theology or doctrinal position. (And this has nothing to do with liberal or conservative theology; it is true across the spectrum. Emotionally healthy leadership seems to attract more diversity of thought and opinion around whatever the spiritual orientation is.)
Another way to think about it is what I learned from evangelical church planters whose training I attended nearly 20 years ago. At the time there was no training available for liberal church planters, at least not that I was aware of. The one teaching that was driven home over and over was that the group of people planting the church must all agree on essential matters of theology and doctrine. Therefore, I was taught, it was very important to hammer out a set of core values that clearly define where you stand on how you read scripture, understand Jesus, think about culture-war issues like homosexuality, etc. The leadership needs to agree on these issues and then when the church gets underway new members also need to be in essential agreement. It is better to say to someone "You know there is another church down the road that might better meet your needs" rather than be so desperate for new people that you welcome those who have fundamental disagreements about core issues. I heard these trainers say that there would be more than enough diversity to deal with even among those who are in agreement on core values.
For the most part we followed this advise as we started Open Circle. I knew starting the church that there were certain issues that were important to me that I no longer wanted to have to be fighting about in a congregation: gays would be welcome, I would not be interpreting scripture in a literal way, and Christianity was not the only valid spiritual path. I was clear about these issues as I talked to potential members and those who stayed were in agreement on these issues. When we had enough of a core group we worked out a set of core values and then we clearly published these in all of our literature. We still do.
In some ways our congregation is not very diverse. We are mostly white, theologically and politically liberal. In other ways we are quite diverse. We have a lot diversity in religious background: Catholic, many flavors of Protestant, pagan, atheist, Jewish. We have a growing diversity in age. We started out with mostly boomer individuals and families; now we run the gamut from young families to seniors, singles, cohabitating and married couple with and without children, gay and straight. We have city dwellers, suburbanites and folks coming from small towns and the country, some driving 30 miles to get to church.
I have found it to be true that even with clearly defined core values there is plenty of diversity that presents continuing opportunities for dialogue and challenges for the congregation as we chart our way forward. We have constant conversations around the issues like these: what does it mean to be a Christian or a follower of Jesus today; how do we relate to our denomination, The Church of the Brethren; how do we best deploy our people resources to serve church and community? We have some strong differences of opinion in the congregation about these issues.
I wish we were more racially diverse than we are and interestingly enough, we were more racially diverse when we started than we are now 17 years later. I am not sure why that is but I would guess that part of it has to do with the fact that I do not have great cross-cultural skills and it is not one of the passions that drives me as a pastor, like say being welcoming to glbt folk does.
It is interesting to note that my answer to this question doesn't even touch on some of the issues found in this response.