That one thing is not what changes are necessary or even why they are necessary. Those are easy enough to discern.
No, the one thing that is necessary for needed change in any organization is the courage of leaders to admit the need and have the courage to act on needed changes. Without the humility to admit that change is needed - and that is humbling - and without the requisite courage to act on that need, nothing happens.
I work with churches and ministry organizations as well as lead ReachGlobal, an international missions organization. The reason I get called in to work with other organizations is that they recognize that not all is well. They are experiencing organizational pain and are looking for solutions.
Finding the source of the pain is not difficult. Convincing the ones experiencing the pain can be. They know that all is not well. But in come cases do not have the courage to act on the necessary steps to solve the problem - which is usually holding them back from much greater ministry effectiveness.
Why is this when it defies logical sense? Because it is more comfortable to live with what we have and the way we have been doing things than to take the risk of doing things differently. Comfort often wins out over mission.
Courageous leaders don't settle for what is when they know what could be. They take the risk to act on needed change in spite of their own comfort and what they are used to. The mission of the ministry is a higher priority than their comfort or even long established paradigms. That is the nature of good leadership.
When asked to help an organization my internal question is always this: Do the leaders have the courage to change? If the answer is no, it is best to leave them with their old paradigms. Don't be one of those leaders!