Now I know we have eco congregations, although they are still largely about lightbulbs and churchyard gardens. You might fondly think that using a bit less electricity is doing your bit for turning the tide of global warming. It isn't – not even close. And it's great if Christians can get involved in the Transition agenda, not least because it calls for significant personal change in local communities, and the Christian faith has a lot of wisdom and power to bring to that.

But don't our churches themselves need a Transition agenda? Just as oil is running out, isn't Christendom running out too? Our churches have long been dependent on the power of Christendom, making all kinds of things possible that local Christian communities could not have done on their own. Christendom made church a very comfortable place to be. As Christendom runs out, many of the ways we are used to 'being church' are becoming unsustainable. We can improve our welcoming processes, we can take out the pews, we can use PowerPoint in the sermons, but these are lightbulb measures. We need to help our churches become resilient and sustainable Christian communities, not dependent on the structures and support of Christendom for their future.

The danger with the 'mixed economy' is that our existing church communities are being assured that they will continue to have a parallel existence much as they are. But if Christendom runs out, most of them won't; and they will run into the coming era ill-equipped to be resilient and sustainable church. In the present battle over resources within the mixed economy, fresh expressions are already beginning to feel the heat. Here in the Diocese of Exeter, out of the 40 or so 'mission posts' promised in our restructuring five years ago, only a handful have seen the light of day and now there is a moratorium on them because of lack of resources. The future of the church could fall between two stools.

David Muir is an Ordained Pioneer Minister in the Okehampton Deanery of Exeter Diocese. With a long background in adult Christian education, he is now supporting 24 largely rural parishes to create fresh expressions of church that will resonate with the increasingly diverse population of Devon. He is also course leader of The Pioneer Disciple, an Anglican/Methodist Devon adaptation of the mission shaped ministry course (see www.exeter.anglican.org/pioneer), and he writes a regular column on how to do church in a 'pioneer' way (see www.exeter.anglican.org/pioneerprimer).

If you have something burning to say and want to contribute to the Share weekly guest blog, please contact Karen Carter. The views expressed in this blog are those of the author and are not necessarily shared by the Church of England, the Methodist Church, the United Reformed Church, Church Army, Fresh Expressions or any of its partners.

The first is when people who have no church background begin to serve the purposes of God in the same way that the 'starter group' first served them. The weakness of some fresh expressions is that the 'serving centre' reflects the culture of mainstream church, well schooled in Christian teaching and practice. So from the start we need to think about how an unchurched person can become a full part of its community life, and begin to serve others as they were once served. It is as if the process has come full circle – like a rope going around something and creating a kind of knot. It secures the day to day life of the fresh expression. If the initial team collapsed, the fresh expression would hold, at least for a time. Before this point the whole rope would simply unravel and all the initial energy would be lost. So from the beginning we need to think about how to get to that first point of sustainability.

Then I wonder if there is a second 'loop' of the rope – when the unchurched person initially served is enabled into leadership. This is like putting a double knot on the rope and securing it properly. So from early on in a fresh expression we need to be looking at people who are being drawn into faith, and asking how these people are going to share in its leadership. If the way we model leadership requires being comfortable with (even keen on) the ways of mainstream church, this fresh expression is never going to become entirely secure. It will always depend on importing leaders with the right credentials. 

Both these tests of sustainability help to focus my mind. In offering to serve others in the name of Christ, can I see how new people can start to help others in the same way they have been served, albeit relying on the grace of God as they do so? Is it too 'expert' a form of service for this to happen very soon? Does it require too much theological understanding, or pastoral expertise, or public speaking skills, or group facilitation skills, or whatever? If so, it is going to be absolutely ages before this fresh expression even achieves the basic level of sustainability. During that time it could fail.

And then, how could ordinary people enter into leadership fairly quickly? Is the leadership task massively complex? Does it require awesome organisational skills? Is it a 'burnout' model that no one in their right mind would take on? Is it deeply fulfilling to do, albeit also a lot of hard work? Is it a shared and meaningful experience, rather than a long and lonely road?

In other words, how can my new fresh expression be something that new members get involved in fairly quickly and the more able ones move into leadership fairly easily?

Does any of that make sense?

David Muir is an Ordained Pioneer Minister in the Okehampton Deanery of Exeter Diocese. With a long background in adult Christian education, he is now supporting 24 largely rural parishes to create fresh expressions of church that will resonate with the increasingly diverse population of Devon. He is also course leader of The Pioneer Disciple, an Anglican/Methodist Devon adaptation of the mission shaped ministry course (see www.exeter.anglican.org/pioneer), and he writes a regular column on how to do church in a 'pioneer' way (see www.exeter.anglican.org/pioneerprimer).

If you have something burning to say and want to contribute to the Share weekly guest blog, please contact Beth Keith.

It includes our first shot at sharing some wisdom on sustainability: Sustaining a fresh expression

Do you agree or disagree with some of the statements made on this page:

• 'Pioneers should withdraw from their converts as quickly as possible.'
• 'Avoid getting bogged down by church events.'
• 'Go back to the drawing board. You can save yourself several years of hard slog on a venture that was never going to last.'

This is far from the last word, and there are almost certainly other themes that we should address. So we need your help.

• What have you learnt about sustainability from your own experience – from triumphs to botches? After reading the material in this section, would you want to say something like: 'No, it's not like that', 'That's far too simplistic' or 'From my own experience, it's really like this...'
• What other themes should this section contain?
• Would you be willing to help us write any of these themes?

Please leave your comments on the pages in this section. We need your wisdom, experience and advice.

Alternatively, when visiting YouTube, type share fresh expressions into the Search box at the top of the page, then click Search. And please spread the word about this video.

If you prefer books to online videos, you might want to check out the latest edition of Encounters on the Edge, number 36: Leading Fresh Expressions: lessons from hindsight. George Lings, director of Church Army's Research Unit - The Sheffield Centre - tells the stories of two fresh expressions pioneers, who are refreshingly honest about the mistakes they have made and what they would do differently now.

Si Jones was leader of Ignite, a youth congregation in Northwood, London. He says, 'Ignite has been the best and the toughest thing I have ever done! There has been a huge cost involved for all people ... not least to my family, where our children were part of a church with only two other children. This cost must not be underestimated as people offer themselves for this form of ministry in the future.'

Looking at the work of Derek Spencer - leader of the Eden youth church in Horsham, Sussex - George Lings says: 'How good in this case he could stop, find support, take advice, and attend to the cracks. He has now come back, ready to move on with a fresh role and deeper wisdom. Many of us know seasons of apparent failures that have been painful but apt tutors.'

Eden is also featured on Share here and here.

Si Jones and Derek Spencer are mission-minded pioneer leaders. In both cases, the emotional and physical energy to plant a fresh expression of church has been huge. How do we look after our pioneers? How do we enable them to plant more than once?

Both stories highlight the high cost of over-investment in the Sunday public event. Stories that start their public life with worship are particularly prone to this.

George Lings says, 'We are grateful to two leaders who were candid about their own stories. It so happens both are examples of youth congregation, but what they saw contains valuable insights for all fresh expressions. In telling these stories I have tried to embed what I see as the many virtues and values as well as the valuable lessons of hindsight. We are still learning.'

Encounters on the Edge 36, Leading Fresh Expressions: lessons from hindsight, is now available and is priced £4.00. To order copies, contact the Sheffield Centre on 0114 272 7451, or email ask@sheffieldcentre.org.uk

The Sheffield Centre website

What Share has to say about Sustaining a fresh expression

It's a vital question, whether you are aiming to grow an existing church or develop a fresh expression. Before you can create or develop something you have to have some idea what it is. Imagine building a car without realising that it needs an engine, trying to put up a house without foundations or baking bread without yeast. All of us in some way are involved in building the church as part of our discipleship. Yet many Christians would be more familiar with the essential elements in a victoria sponge than they are with the really essential elements in a church. 

You will need to make sure everyone has a copy of the list in the box below and a pen. Ask the group to break into pairs and go through the different attributes. If you have plenty of time, invite people to:

1. Circle the elements which you would you say are essential to form a church
2. Underline the elements which are desirable and helpful
3. Delete the elements which are unhelpful
4. Leave unmarked the elements which are neutral or depend on context
5. Feel free to add other essential elements

When you have been through the lists, compare your answers.

If you are short of time then just concentrate on the first task: see if you can reach a short list you can agree on in terms of the essential elements in forming a church.

As I've played this game with different groups over the last six months, I have come to believe that just three elements are part of the essence of what it means to be the church. They come up in every set of responses. My answers are in the box at the bottom of the page. Resist the temptation to read them until you've at least had a go at the game yourself. I may be wrong! I also believe that three other elements are essential to maintain and build a healthy community. Everything else is either desirable, merely convenient or helpful or not according to context.

You may or may not agree with my answers (and please let me know). However, what often emerges from the exercise is surprising agreement about these elements and a realisation that it is often the non-essential elements which take up so much time and energy.

The second part of the game is to begin to explore more deeply how we decide what is right and wrong about the life of the church. A good way to begin is to invite people to suggest their own key verses for thinking about the life of the Christian community. Where do they go in Scripture and in the Christian tradition for thinking about what it means to be the people of God?

There is no right answer here. In fact, the more places we look, the more our understanding grows. The more we look, the more we discover that our understanding of the church can't be contained by just one proof text or just one summary of Christian teaching (such as the marks of the church in the creed). But here, to finish, is one key passage which I continue to find helpful.

In Mark 3.14 we read of Jesus' call of the twelve disciples. This is a passage which speaks hints of new Israel: it is deliberately about the forming of a new community. Mark has distilled the essential elements of what it means to be the community of disciples – the beginnings of the church. What are the essential elements?

'And he appointed twelve, whom he also named apostles, to be with him, and to be sent out...'

The essence of being church according to Mark is people being called by Jesus to live in the rhythm of being with Christ and being sent. If you read on in the verse you discover what we are sent to do: to proclaim the good news and to overcome evil in the world.

This is the kind of community we are called to become and to build.

My own answers to the game:

Three essential elements in being the church: people, the risen Christ and mission to God's world.

Three essential elements to sustain the church: the Scriptures; the sacraments and connection and oversight.

Are fresh expressions proper church?