On the best reading of it parachurch organisations make use of minimal statements of essential gospel truths in order to unite the maximum number of people for the purpose of achieving a specific and limited goal. It is also true to say that some churches who participate in parachurch enterprises share, or even have adopted, a statement of faith belonging to a parachurch organisation.
These two positions can be characterised in the following way:
1. Hold to fuller and longer statements and confessions (e.g. Westminster, Savoy, London Baptist). By a fuller, longer statement I mean one that covers more areas of biblical truth and church life, and one that covers each area in greater detail. These fuller statements not only incorporate doctrine, but also ethics (10 commandments) and piety (Lord's prayer).
2. Use confessional statements in the positive teaching of the church (especially among children and youth) as well as in the appointing, and when necessary, the discipline of ministers and church officers.
1. Hold to shorter statements of faith with less unpacking of the positive meaning of each subject.
For example, the Evangelical Alliance (UK) basis of faith states that "We believe in  The justification of sinners solely by the grace of God through faith in Christ." By comparison the Westminster Confession chapter 11 deals with justification under six headings and has a word count of 388.
2. Most likely use statements of faith in the appointing, and where necessary, disciplining of ministers and church officers. It is more likely that doctrine will be taught subject by subject, if at all, with little emphasis on the need for or importance of ecclesiastical confessional statements.
With widely divergent approaches to the idea of confessionalism it is no wonder that evangelical relationships are often fractured and tense. The tensions being caused not perhaps by individual doctrines so much as approaches to doctrine itself that are poles apart.
Even when doctrinal statements are treated with some reservation, it is in fact impossible to avoid making and acting on doctrinal convictions on areas covered by a minimal statement of faith, as well as in church practice, ethics and piety. When that happens we end up with both written and unwritten statements of belief and practice in operation. We may even have the strange situation where written statements are devalued and unwritten ones are used with significant authority (this situation is particularly noticeable in Brethren circles but applies more widely).
Some comments by Terry Virgo in his interview earlier this year with Adrian Warnock illustrate this point. Terry Virgo adopts a surprisingly negative view of the role of written statements of faith (not, however, of the importance of doctrine) but at the same time has a clear view of the essential nature of a number of other truths, that are unwritten, for New Frontiers churches:
"We don't in fact have a statement of faith, because I wouldn't want to be defining in a kind of way that can put people in a kind of prison. I have met many people who belong to movements which have clearly articulated statements of faith and practice but they don't personally embrace everything that the movement says. They say, 'I belong but I don't believe everything in it.'Followed by:
We happily embrace the classic creeds and statements of faith without getting into tight definitions of detail, which can put people into a prison.
I can't see that the early Church as described in the Bible had a systematic theology kind of statement of their faith. Obviously Apostolic doctrine was fundamental. The Apostle Paul taught doctrine, and they devoted themselves to the Apostles doctrine. But the very concept of a statement of faith seems somehow foreign to the atmosphere of the Bible and the early church."
"We would embrace the final authority of Scripture and that the Bible teaches, for instance, baptism of believers by immersion and we would say without that you could not be part of Newfrontiers. We would hold that as essential. Sometimes Anglican communities have asked if they could be part of Newfrontiers and I have said 'No' because we would hold that to be essential.In point of fact they do relate by doctrinal statements, but those statements are unwritten and rely on the relational commitment of church leaders to maintain them and enforce them.
It would also be essential to believe that there are apostles today and that local churches are autonomous and work within an apostolic sphere. We are a charismatic group, so believe that the gifts of the Holy Spirit continue. We believe in the centrality of worship, and would want to see the presence of God manifest in meetings of churches wanting to join...Though we are diligent for truth, we relate in and through churches rather than by doctrinal statements."
This opens up a number of questions. How do you determine what "the final authority of Scripture" is if you do not have a statement of faith that defines, explains and defends it? Do you take a straw poll of the churches? How would you know if that commitment to the "final authority of Scripture" carried the same meaning from church to church without a formal, written, voluntary agreement on what it meant? How could you adminster discipline on that matter if a church went into error even though they maintained that they were still upholding the "final authority of Scripture"? On what basis could you evaluate the beliefs of a church seeking to join the wider family of churches?
To do that relationally (and after all it is men who have to discuss and decide these things), still requires a standard by which to confirm and evaluate specific doctrinal convictions. If I want to know what the church down the road believes about the authority of Scripture and I can't find a statement of faith I will want the minister to tell me what he believes. When he does so I will be wondering if his views correspond to what I believe Scripture to teach about its own authority. Neither of us can escape definitions or statements of faith when we express what we believe about the final authority of Scripture. So it is not as if being confessional and relational are inherently opposed. Sharing a common confession is surely part and parcel of how churches relate. To oppose them is to confuse categories.
Far from being a prison, confessional statements bring clarity, unity in the truth, and accountability to church relationships. The great fault of unwritten approaches to essential matters is that they undermine, intentionally or otherwise, clarity, unity and accountability. What someone considers to be essential may be unwritten but it still has to be verbalised. Whether it is in words written on a page, or spoken, it is still expressed in words. So why not write it down? Can you think of a good reason not to?
Fuller confessional statements do not place churches in error free zones, but they do make it easier to deal with problems when they arise because.