Evidence

Usually, if you decapitate an organizations leadership, the movement will die, or at least recede. This was the Romans idea when they (allegedly) carried out the execution of Jesus in about 30 AD. The disciples were afterwards demoralized, yet something seemed to happen that energized the tiny, scattered band of believers, enough to cause them (save one) to go on to eventual martyrdom. In this instance the execution of the leader failed, the movement flourished- enough so that by 64 AD (34 years later) enough Christians existed to become a handy scapegoat for the burning of Rome.
What happened that turned a rag-tag bunch of frightened and hiding followers into an inspired vanguard?