Michael Green puts it well, I think:-
I miss this note of witness-bearing in contemporary Christianity. Many preachers bring carefully prepared scripts which they read with greater or less skill and conviction. But rarely do they let you know that this stuff is their very life blood. Rarely do they allow their own discovery of Jesus, their own profound convictions about him, the difference he has made tot heir own lives, to surface in their address. I do not know whether they think this is out of date, or mbarrassing. I do know that sermons devoid of witness are drearily boring. I wnat to hear what Jesus can do to men of flesh and blood like me. I want it from the Scriptures, but I want it from the life too, and that is why witness is such an important part of the proclamation of the gospel. Often two minutes of honest testimony, the more broken and unschooled the better, is worth twenty minutes of eloquent discourse by some silver-tongued preacher. The early Christians knew this. They were not all preachers, but they were all witnesses. And they expected every Christian to have something to say about Jesus and the difference that Jesus makes to life. And where that happens in the world today, the church grows and people come to faith.
Acts for today, 87