The Bible says, "Where there is no vision, the people perish." Proverbs 29:18 (KJV)
18 Where there is no vision, the people are unrestrained, Proverbs 29:18 (NASB)
In the original language the idea is that where there is no vision the people throw off restraint, they have nothing to keep them disciplined. Maybe one way of looking at this is that the concept of vision helps keep everyone on the same page, moving together as a group, with one purpose in mind. Without a vision everybody does their own thing, sets their own agenda, and ends up competing with each other so their way wins out. Vision is crucial to the health and success of a church.