To stay united (or appear to be), members of families, religious groups, social movements and political parties may play down doubts and disagreements.
On minor matters, this may be sensible or at least harmless. However, when this involves upholding injustice and cruelty, it can damage not only those on the receiving end but also the cause which is supposedly being championed. For instance, those Communists who swallowed their misgivings about Stalin's purges did a grave disservice to the ideals in which they believed.
Though harmony may be a great virtue, others such as compassion and truth cannot be ignored. And on a practical level, while "singing from the same hymn-sheet" may reinforce a particular message or ideology, this may not work if the tune is off-key. Not all, however, would appear to agree.
For instance, the Archbishop of Canterbury, Rowan Williams, in his July 2009 "reflections", Communion, Covenant and our Anglican Future, argued against increasing acceptance of same-sex partnerships by the Episcopal church. One of his reasons was that the approval of the universal church – the "church catholic" – was needed.
His claim that no church "is free to recognise same-sex unions by means of public blessings that are seen as being, at the very least, analogous to Christian marriage" has wider implications for ethical decision-making as a whole.
He argued against this in part because of "the way in which the church has consistently read the Bible for the last two thousand years". Any change "would have to be based on the most painstaking biblical exegesis and on a wide acceptance of the results within the communion, with due account taken of the teachings of ecumenical partners also.
"A major change naturally needs a strong level of consensus and solid theological grounding. This is not our situation in the communion. Thus a blessing for a same-sex union cannot have the authority of the church catholic, or even of the communion as a whole."
In reality, there are few, if any, issues on which Biblical interpretation has not varied and many would feel that a strong theological case has now been made for celebrating loving and faithful partnerships, whether gay or straight.
However, it is true that Anglican churches in some countries have refused even to consider the possibility and the Roman Catholic and Orthodox churches are unlikely to relax their position in the immediate future.
Historically, Anglicans have often acted controversially, from breaking away from the pope's control centuries ago and allowing ordinary people to read the Bible, to ordaining women.
International Anglican gatherings in recent decades have acknowledged a "debt to the host of devoted scholars who, worshipping the God of Truth, have enriched and deepened our understanding of the Bible, not least by facing with intellectual integrity the questions raised by modern knowledge and modern criticism", and urged "every diocese in our communion to consider how through its structures it may encourage its members to see that a true Christian spirituality involves a concern for God's justice in the world, particularly in its own community".
Dr Williams' view by no means reflects Anglican tradition. And it is not certain that even he would be willing to hold this principle sacred.
For instance, in the 16th and 17th centuries, extreme antisemitism was common in Europe, along with witch-hunting and other forms of persecution. Different churches, at odds over other matters, often encouraged this, supposedly justified by a reading of scripture which took passages out of context and ignored the vital importance of justice and mercy.
Were those who stood against this tide of bigotry, such as Ladislaus IV of Poland who forbade the printing of antisemitic material, wrong? It is doubtful that Dr Williams would think so. Indeed, in a Remembrance Day sermon, he spoke of the need "to fight off easy answers, false gods, stifling systems". And in Rome recently, he suggested that disagreement on some matters does not necessarily prevent unity on others.
Those who see through the prejudices and errors of their era sometimes have a responsibility to act. Complex matters cannot rightly be decided on the basis of unity – let alone uniformity – at any cost.
© Savitri Hensman was born in Sri Lanka. She works in the voluntary sector in community care and equalities in the UK, and she is also a respected writer on Christianity and social justice. An Ekklesia associate, Savi has contributed several chapters to the recent book Fear or Freedom? Why a warring church must change , edited by Simon Barrow (Shoving Leopard / Ekklesia, 2008). She has written and reflected widely on the future of Anglicanism and is herself a member of the Church of England.
This article is adapted with acknowledgements from her Guardian Comment-is-Free column. http://www.guardian.co.uk/profile/savitrihensman 
See also the detailed Ekklesia research essay, 'A better future for the Anglican Communion' - http://www.ekklesia.co.uk/node/10247