The meaning of the word:
A witness is one who has seen or heard something and is therefore competent to give evidence about it. The disciples were curious about the timing of future events and asked the Lord about this in Acts 1:5. He replied that these matters the Father reserved to be revealed in proper time, but for now, the assignment which was to concern the disciples was to be His witnesses. Note four facts of interest about verses 7-8. In the first place the disciples were to be witnesses to a person; the Lord Jesus Himself. They were not commissioned as witnesses to doctrinal truth, to a church, or even to the church, but “witnesses unto me.”
Second, we note that this would not begin until the Holy Spirit was received. Witnessing for Christ will not be effective unless carried out in the power of the Holy Spirit. He alone can convict the world (John 16:7-11) and give the disciple boldness and power. In the third place, we observe that the Lord did not use the word “evangelists .” The difference between the witness and the evangelist must be understood. Simply stated, the witness responds and the evangelist initiates. Not all believers are evangelists as that is one of many spiritual gifts, but every believer is a witness, i.e., has seen and heard something to which he can testify when questioned. Finally, we note that the sphere of the witnesses began closest to home and widened out to the ends of the earth, providing a principle that must be observed; one who claims a burdened for those far away should begin first to tell those close at hand.
The inspired outworking of this truth:
A careful study of the first seven chapters of the book of Acts will show how seriously the disciples treated this pronouncement from the Lord. The word “witness” is found in every one of the first seven chapters of the book! Thousands are saved and specific count gives way to the expression “multitudes,” and all of this before any detailed example of the work of the evangelist which begins with Phillip in Acts 8. Furthermore, it is interesting to trace the way in which the disciples worked, for it can be seen immediately that in every case, their witness came in response to questions express or implied. Let’s list the passages to make this point clear.