I've been pondering this while watching the Man Utd - Madrid match. Football clubs are in many ways classical co-opertitive (I hate the spelling "coopetitive", don't you?) entities.
Let's take the old rivalry - skewed by management incompetence on one side and a genius on the other for the last two decades, sadly - between Liverpool and Man Utd. They are competitive. Or they were, at any rate. But although they compete, it is in each club's interests that the other remain in existence. Liverpool v Man Utd is guaranteed to sell out, adds glamour to the Premier League, generates knock-on sales in shirts, and happens to improve lager sales across the country. The rivalry is good for both, and others. In a purely dog-eat-dog world, one football club would seek so to dominate the league that all other clubs went bust. But, like wolves eating the last rabbit on an island, that's in nobody's best interests. So clubs set up leagues - agree the rules. Use concepts like "financial fair play", transfer windows - in some sports even salary caps - to obtain, if not a level playing field, at least one that isn't sloped like the North Face of the Eiger.
Even grocery retailers, those most red-in-tooth-and-claw of capitalists, indulge in a certain degree of co-opertition. The humble barcode, for example. If every grocer insisted on its own barcode format and numbering system, costs would be driven into the supply chain for everyone. And so, with suitable rules to prevent anti-competitive behaviour, the (Global Standards) GS1 group manage barcode rules for everyone's benefit.
But where do Churches lie on this spectrum? In theory, at least, the more moderate Protestant groups should act is a completely uncompetitive, disinterested manner - why should the Methodist chapel worry if the C of E is gaining lots of followers, as long as people are being saved? Going beyond the moderate co-opertition described above, churches should happily serve each other - ensuring that people go to the church where they feel most comfortable, regardless of denomination. They should cheerfully share resources, so that the best result for the Kingdom should be found across a locality - each making sacrifices for the other where required; recommending people go somewhere else if it seems more appropriate; sinking differences for the good of all. It might be more difficult out on the fringes (the 1 bn on the Catholic fringe, and the couple of hundred million on the Pentecostal fringe...) but even there there, at least most Pentecostals can regard other Pentecostals as being vaguely Christian, can't they?
I guess the thing is, some Christians see the differences between denominations as being the difference between eternal, blessed, wonderful life and a nasty, sizzly, eternal smell of burning in the nose. Which tends to focus the mind. I could give you examples of the websites that give an insight into this kind of thing, but I won't. It's bad for the soul.
I'm not sure what I'm trying to say here, apart from "Have you heard the one about the one body?" and "why can't we all just get along?" So I'll finish with this instead. If grocery chains got on as badly as some church groups, their adverts would consist entirely of telling you that their competitors' food rots your teeth, their soap powder dissolves your clothes and their staff put kittens on spikes for fun. While the advertisers' exactly-the-same products would guarantee eternal life and perfectly white teeth. If one store manager at another chain got done for "taking the work home with them", the other chains would accuse every member of staff at that chain of being criminals. And when a store closed due to lack of trade, all their competitors would celebrate the loss of jobs. That can't be right, can it?