Doubt is both the cause and the antidote for evangelism.
A believer who never doubts, also never question examines their own believes. The evangelist is the worst evangelist, and the greatest detractor to their own religion or movement.
But the narcissist is an evangelist for itself, and narcissism is often an excess of self doubt. Too much for a spirit to handle, a great deal of doubt becomes denial and delusion.
Doubt is the sunlight we need to grow; Doubt is what drives into the dark.