Absolutely nothing will revitalize a discouraged church faster than rediscovering it's purpose.
Longing for the ideal while criticizing the real is evidence of immaturity. On the other hand, settling for the real without striving for the ideal is complacency. Maturity is living with the tension.
You can only make a difference by being different.
There is no growth without change, and there is no change without loss.
Patience puts up with those you'd like to put down
Many believe one can be a "good Christian" without joining (or even attending) a local church, but God would strongly disagree.