First, the city of Sardis was able to be captured twice because its Sentries were asleep on the job. They were supposed to be the first line of defense, the wall of security. They failed, thus Sardis was captured. I believe the pastors, deacons and elders represent the Sentries of the Church. When they are asleep on the job, have grown complacent, comfortable and content, the Church becomes vulnerable to attacks and captured by the enemy.
Secondly, no manmade program can bring life to the Church. Life can only be brought to the Church by the Spirit. When the Spirit is "grieved" the life of the Church evaporates. But when Believers confess and repent their sin; make amends with God and each other, the Spirit is invited in and revival can take place.
Thirdly, where there is no persecution it is evidence that the enemy's territory hasn't been invaded. What I mean is that Satan hasn't felt threatened, therefore He doesn't attack. In other words, if everything is comfortable and calm in the Church, it's most likely because the Church's witness isn't aggressive enough to threaten Satan. "No friction usually means no motion!"-Warren Wiesrbe. When the world sees the Church as respectable and agreeable that should indicate to its Believers that something is wrong because the Church is seen as neither dangerous or desirable.
When something is alive there is evidence of growth, mending, reproduction and power. Otherwise, it's dead. So to the Church, "Wake-up! Be watchful! Repent! Remember the Word you have received and obey it!"