"The content of our message is Christ and God, not our journey to faith. Our personal testimony may be included, but witnessing is more than reciting our spiritual autobiography. Specific truths about a specific person are the subject of our proclamation. A message has been committed to us--a word of reconciliation to the world (2 Cor. 5:19).
Good evaluation questions to keep in mind after hearing a testimony are "How much did I learn about Christ? How much about the speaker? Which was more prominent?" When people are very much in love, you find them expressing many things about their loved one and not always focusing on themselves. I still remember the change that came over and especially shy girl every time she got the chance to talk about her boyfriend. You couldn't keep her quiet! It is the same with a healthy testimony about our lover Christ.
Why is it important to distinguish between gospel truths and testimony? In an age of religious pluralism, we find many who are testifying. I'll never forget the time when I had been speaking to a young man about the change Christ had made in my life. His sincere response was, "Listening to New Age music does the same for me." What would you have said in reply? Some people recommend faith in a guru or in a technique of meditation or in self or in relationships. Many cite experiences of a change in life. If our witness has no truth content, we can expect the typical response: "That's interesting. I'm glad for you, but what you have isn't for me." Can you imagine the apostle Paul saying, "I just have this warm feeling in my heart"?
Faith is not to be looked on as a separate entity ("I wish I had your faith") but as an ability given by God that is valid only because it connects us with Jesus Christ. It is worth noting that the New Testament Christians never attempted to establish the truth of Christianity on their inward experiences...To put it another way, never do we find Paul trying to prove the truth of Christianity to others 'because of the difference it has made in my life.' (Will Metzger, "Tell the Truth", pgs. 27-28 )