All Christians should be evangelists - sharing the good news of Jesus Christ with others. I often wonder whether an evangelist is more like a salesperson or a scholar. I see these two as polar opposites: the salesperson is so sure of his/her product - s/he is both inwardly convinced and outwardly convincing, whereas the scholar is never certain - s/he is continually doubting, searching, striving...
Somehow, the evangelist needs to combine the best of both these personality types. Jesus' injunction to Thomas 'Be not faithless but believing' means we should be convinced of our message about the risen Christ. On the other hand, Paul's confession that he had 'not yet reached his goal' sounds much more like a careful, conscientious scholar than a cocksure salesman. Remarkably, this tallies with Bertrand Russell's view of wisdom and folly.
I guess Jesus himself is the perfect role-model for Christians - confident in meekness and meek in confidence [Matt. 5v5].
