Did you know that for over two hundred years people believed that California was an island?
It happened innocently enough in 1539 when explorer Hernan Cortez was sent from Spain to search for an idyllic island in the area. After a long journey supplies ran low, so he made an educated guess, having sailed up the Gulf of Baja for hundreds of miles with land on both sides and water ahead and behind him, he turned back and excitedly told the king and queen that he'd found the island.
This belief was reinforced by future inadequately equipped expeditions. Soon, maps were printed, people were educated, and the physical map became the mental reality. Though expeditions as early as 40 years afterwards found that it was in fact a peninsula, "the island of California" was accepted as truth for 200 years.
Why did it take so long to change the map? If you see a map long enough it becomes the map, not a map. Once our beliefs become fixed we interpret all new data through the lens of that "reality".
The same thing happens in churches. Once programs are set and traditions are established they become the way, not simply a way. Whether organizations are large or small, the calcification occurs in the minds of individuals. The first barrier to creating significant cultural change is redrawing those mental maps. It's a difficult process, no one likes to hear that their map shows an island that's really a peninsula.
Lasting change is easy to talk about, but difficult to enact. To enact meaningful change we must be willing to place our mental maps on the table and be open to revision.