But ye shall receive power, after that the Holy Ghost is come upon you: and ye shall be witnesses unto me both in Jerusalem, and in all Judea, and in Samaria, and unto the uttermost part of the earth. Acts 1:8
Jesus had a plan. A successful mission is not something that just happens. It needs thought, direction, and power. The first step in Jesus' massive plan was for His followers to be fully equipped for their daunting task. That would take not only knowledge, which He had supplied them with while He was on earth, but divine power.
The Greek word for "power" is dynamis, from which we derive our word "dynamite." I vividly remember a trip I took across the desert of southern California nearly 50 years ago. What caught my attention was a blinding flash on a mountain some miles in the distance. Next, I saw a huge cloud of dirt and debris. At that point the first sound waves shook my car, and I realized that I had witnessed a mighty explosion. The explosive agent in that case had undoubtedly been dynamite. Dynamite is a form of dynamis or power. Paul ties the gospel message to that same force when he writes that "the gospel...is the power of God that brings salvation to everyone who believes" (Rom. 1:16, NIV).
One reason that he is not ashamed of the gospel is that it is backed by God's power. And one thing the apostle makes crystal clear in the early chapters of Romans is that people are unable to save themselves from the hold of sin. No matter how hard they try, they can't free themselves from its ravages. That's where God's power comes in. He can do what we cannot.
That truth applies to both the saving of sinners and the spreading of the truth of the gospel. And it is the Holy Spirit who is God's agent in those tasks. The work of the Spirit undergirds all true Christian evangelism. Without the Spirit there is no dynamis.
That brings us to part 2 in Jesus' mission plan. He calls His Spirit-empowered followers to be His agents or witnesses. Here we find another important Greek word, martys, from which we get the English word "martyr." Originally the word stood for someone bearing witness in a court of law. But in the New Testament it came to mean one who witnessed or bore testimony to the truth of the gospel of Christ. Eventually it signified someone willing to die rather than give up Jesus and the preaching of His message.
God is still calling people to be His witnesses in power. Today He is summoning me and you personally. How shall we respond?