One day I decided to seek my own definitions of these ideas. First, I looked up the words in the dictionary. To my surprise, I found a simple and common sensical definition there; to witness or testify just means to "tell what you know or have experienced" about a particular situation or concept.
Shortly thereafter I was reading a story from Jesus' life. He was engaged in teaching the people who followed him when He and His followers noticed a beggar who was blind, and had been blind since birth. Jesus' followers descended from a tradition that all infirmity resulted from one's sin or the sins of one's parents, so they inquired, "Rabbi, who sinned, this man or his parents, that he would be born blind?" (John 9:2, NASB) Jesus responded that sin was not the cause of his blindness, but that the man's blindness was about to become a root of faith for many people. Then, He gave the man his sight.
This event seriously upset Jesus' enemies. They responded by hauling the healed man in for questioning. When he arrived they told him that they were convinced that Jesus was a "sinner" and questioned the means by which He had healed the man. The former beggar replied, "Whether He is a sinner, I do not know; one thing I do know, that though I was blind, now I see." (John 9:25) His questioners continued to pound away at him for the purpose of undermining Jesus' credibility. Finally, the exasperated man snapped,
Well, here is an amazing thing, that you do not know where He is from, and yet he opened my eyes. We know that God does not hear sinners; but if anyone is God-fearing and does His will, He hears him. Since the beginning of time it has never been heard that anyone opened the eyes of a person born blind. (John 9:30-32)
I suddenly realized that this poor beggar had never studied any courses in witnessing or testifying. He was not willing to state anything that he did not know or had not experienced. However, he was willing to fearlessly tell what had happened to him personally, even in the face of a threatening situation. I believe this is how God wants us to witness and testify to others. He just wants us to tell others what He has done for us personally.
Since that time I have never had any problem with witnessing or giving testimony. I understand that God simply wants me to tell the people around me what he has done for me. Before I accepted God's gift of redemption from sin, I was confused, unhappy and afraid. Then someone told me that Jesus was coming by and wanted to heal my spirit. In my desperation I consented. The result: Clarity of mind, happiness and confidence. How did He do it? I don't know, but if you had known me before you would certainly know that He did. I'm no longer sitting by the side of the road and begging.
For more information about Christian Hope, I recommend the blog My Piece of Pi.