Yes this is interesting TillICollapse and aslo problematic because I think many Christian witness accounts are dubious, and therefor detrimental to the Christian model.
A lot of pastors try to make every member an evangelist even when scripture plainly says otherwise.
In the New Testament model, an evangelist is called to that role and gifted specifically for it by the Holy Spirit, is thorougly trained in theology by the church, is commissioned to a specific mission by the church, and is then held accountable to the church for his missionary activity.
Everyone is not an evangelist, but everyone is called to be a witness to what he or she has personally experienced.
Then they [the Sanhedrin] called them in again and commanded them not to speak or teach at all in the name of Jesus. But Peter and John replied, Which is right in Gods eyes: to listen to you, or to him? You be the judges! As for us, we cannot help speaking about what we have seen and heard. -- Acts 4
Peter and John challenged the Sanhedrin to make their own judgment over whether Peter and John should testify to what they had seen and heard. The Sanhedrin were the judges of Israel, and the basis of their judgments was the Mosaic Law. In Leviticus 5, the Mosaic law declares that failure to testify to what one has seen and heard is a sin.
Testifying to what you have experienced requires no training in theology--the Samaritan woman wasn't even sure Jesus was the Messiah, yet she was a hugely effective witness. The blind man healed by Jesus was another example:
So they again called the man who was blind, and said to him, Give God the glory! We know that this Man is a sinner.
He answered and said, Whether He is a sinner or not I do not know. One thing I know: that though I was blind, now I see.
Then they said to him again, What did He do to you? How did He open your eyes?
He answered them, I told you already, and you did not listen. Why do you want to hear it again? Do you also want to become His disciples? -- Mark 8
Notice again that the witness doesn't know theology--he does not know what Jesus is about. But he has his testimony. Not everyone is going to accept the testimony of the witness. Oh, well. But his testimony is still his testimony.