I think often about a quote from George Romney, who at the time was running American Motors. Remember American Motors? They produced some amazing cars, like the "Mirthmobile" from Wayne's World:
Yes, the Pacer was quite a car. Have you noticed that American Motors isn't much of a going concern these days?
What George Romney said was this: "There is nothing so vulnerable as entrenched success."
This is a powerful statement not only for car companies, but for churches. Because churches have institutional memory entrenched in the sensibilities of the members, we are incredibly vulnerable to what used to work.
Churches find themselves mediating between the unchanging truth of the good news of Jesus, on the one hand, and the ever-changing specifics of culture on the other. So while the church's message doesn't ever change, the churches methods must change frequently.
And by the way, Christianity will rarely find success going back to something that used to work ten or fifty or a hundred years ago.
I'm reading lately about "radical traditionalism" -- the need for churches to delve into their past to find the nuggets of mission, the nuggets of how specifically God sent this church into the world. Then those nuggets have to be recast for the present day. One great example of this is churches that have grabbed hold of Martin Luther's statement about home-based worship and have recast it for the present day when missional communities (pastorates) are springing up across the world. It's a radical way of re-appropriating our tradition.
Beware entrenched success. It's what the railroad barons had when someone showed them plans for a gasoline powered truck, and they scoffed, saying "We're in the railroad business." They didn't realize they were in the transportation business.
It's what the Swiss watchmakers had when, in the 1950's, someone showed them a digital watch and they scoffed. The inventor went to the Japanese manufacturers with it.
It's what Kodak had when they rejected digital photography, believing instead that they were in the business of making film.
Nothing is so vulnerable as entrenched success.