I can just imagine the conversation. Henry VIII has just informed one of his advisers of his plan to separate the Church of England from the Roman Catholic Church. His adviser, incredulous, tries to make him reconsider. "The Roman Catholics have already separated from the orthodox Christians - if we bring any more factions into it, it'll never end! We're just going to end up fighting one another and everyone will stop believing in Christ and Christianity will DIE!" Or words to that effect.
His adviser was partly right, of course. The Christian faith now encompasses Protestants, Catholics, Baptists, Methodists, Lutherans, Evangelicals, Presbyterians and many more besides. And, to give Fictional Adviser his due, there has been a fair bit of fighting between those groups since 1534. And yet, even with religious observance declining across the board, the teaching of Jesus Christ shows no sign of fading into obscurity - Christianity is the world's dominant faith, with over two billion followers, and remains a powerful (sometimes the powerful) force in politics, economics and society across the globe. Not bad for a bunch of infighting splinter groups.
Another set of warring tribes that have done alright are Feminists. That umbrella term encompasses Liberal Feminists, Radical Feminists, Marxist Feminists, Socialist Feminists, Cultural Feminists, Eco Feminists, Queer Feminists - and yes, those groups have been known, on occasion, to disagree. In fact, feminists still disagree with each other to the extent that they frequently take diametrically opposing positions on key issues and occasionally deny that other factions even really exist. And yet there are more people self-identifying as feminists than there have ever been, and feminism is more influential, understood and discussed than ever before. How about that.
How do these broad ideologies manage to carry on, and even prosper, in spite of this unremitting subgrouping? They don't. They carry on - and prosper - because of it.
Because these aren't splinters. They're roots.
A splinter is a tiny piece that breaks away from the whole. A root is something that takes its own direction but ultimately remains firmly fixed to the same centre as all the others. And wide roots make a strong foundation as long as they centre in the same place.
The success of Christianity and Feminism is, in part, due to their ability to appeal to a range of different people. If you had to be an Evangelical Christian to be a Christian, they wouldn't be a big enough group to pressure the American government. If I had to deny the existence of trans* women in order to stay 'on message', that'd be one less voice in the feminist fight. The first point to consider is the sheer weight of numbers, and the fact that giving people choice within a movement will ultimately give the movement as a whole more clout.
But the main point is that it is can still be one movement, however much diversity there is within it. If you're actually in that movement, or working for an ideologically driven news outlet opposed to it, it's easy and tempting to focus on the differences. The many, sweeping similarities are too obvious to dwell on - no one spends an evening vigorously agreeing on twitter.
But to the outside, it's the similarities that count. We don't actually have to simplify our message so that people understand it - people will do that for themselves. Its "The Church" that successfully lobby governments the world over. It was "Feminists" that are changing laws, hearts and minds. Yes, feminists are still debating issues such as sex work, but the increased influence of the feminist brand means there are more voices on both sides of that debate. Okay, Christians still haven't decided whether 'No Sex Before Marriage' is a rule or a suggestion, but that's really a matter for them. The more important point is that where there is consensus, whether on abortion, poverty, equal pay, they come together as a force to be reckoned with.
The Labour Party, and their most determined critics, may do well to remember this in the next few years. Those hysterically bemoaning that there are 'too many Labour groups to count' are, by definition, either scaremongers or people that can't count to ten. But they aren't just exaggerating a problem, they're creating one. If any of those that feel a loose connection to our values find a stronger, more personal connection in Momentum, Progress or Open Labour then these groups are making us stronger as a party. They are not dividing a party but bringing more people into it, under the same banner. Yes, there are heated discussions, even bad behaviour from individual members of each group - also true of Christians, Feminists and plenty more besides. But, as usual, there are more people quietly being reasonable and dedicated, not just to their cause but to the cause in general.
When it's time to work on something that we all agree on, whether its saying Yes to the EU or No to David Cameron, (neither issues that Tory back benchers seem that unified on...) there is no reason to assume we'll be less effective for all of our partner groups.
As a matter of fact, the evidence suggests quite the opposite.