“But you shall receive power when the Holy Spirit has come upon you; and you shall be witnesses to Me in Jerusalem, and in all Judea and Samaria, and to the end of the earth.”  Acts l:8

These were the last words Jesus spoke to the disciples as we see in Acts 1:9
“Now when He has spoken these things, while they watched, He was taken up, and the clouds received Him out of their sight.”  Acts 1:9

Concerning the Holy Spirit:
Jesus tells His disciples in His last discourse with them at the ‘last supper’,
“And I will pray the Father, and He will give you another Helper, that He may abide with you forever, 
 even the Spirit of truth, whom the world cannot receive, because it neither sees Him nor knows Him; but you know Him, for He dwells with you and will be in you.”  John 14:16-17

Acts 2:1-4 tells us of the filling of the Holy Spirit:
“Now when the Day of Pentecost had fully come, they were all with one accord in one place.  
 And suddenly there came a sound from heaven, as of a mighty wind, and it filled the whole house where they were sitting.  
 Then there appeared to them divided tongues, as of fire, and one sat upon  each of them.  
 And they were filled with the Holy Spirit and began to speak in other tongues, as the Spirit gave them utterance.”  

It is several verses later that Peter gave the first gospel sermon, witnessing to all who were in Jerusalem at that time.  Verses 5-12 tells of the different language groups that were there in Jerusalem (I counted 15). 

Let us see what Scripture tells us concerning Jesus’ command to His disciples (who we are also) concerning witnessing (bearing testimony to)  the world the Good News, the Gospel.

It is the gospel-- 
Of God
“Paul, a servant of Jesus Christ, called to be an apostle, separated to the gospel of God.”  Romans 1:1

Of Christ:
“When I came to Troas to preach the gospel of Christ, even though the door was opened for me in the Lord, my spirit was not at rest…”  2 Corinthians 2:12

Of the Kingdom:
“And this gospel of the kingdom will be proclaimed throughout the whole world as a testimony to all nations…”  Matthew 24:14

Of the grace of God:
Paul speaking,
“But I do not account my life of any value nor as precious to myself, if only I may finish my course and the ministry that I received from the Lord Jesus, to testify to the gospel of the grace of God.” Acts 20:24 

Of peace:
As part of the armor of God so that we can stand firm, as seen in Ephesians 6:15,
“and having shod your feet with the preparation of the gospel of peace.”

O salvation:
“In Him you also trusted, after you heard the word of truth, the gospel of your salvation; in whom also, having believed, you were sealed with the Holy Spirit of promise.”  Ephesians 1:13

The gospel is the source of hope,
“If indeed you continue in the faith, stable and steadfast, not shifting from the hope of the gospel that  you heard, which as been proclaimed in all creation under heaven, and which I, Paul, became a minister.”  Colossians 1:23

The gospel is the source of salvation:
“But we are bound to give thanks to God always for you, brethren beloved by the Lord, because God from the beginning chose you for salvation through sanctification by the Spirit and belief in the truth, to which He called you by our gospel for the obtaining of the glory of our Lord Jesus Christ.”  2 Thessalonians 2:13-14

I quote Robert J. Morgan from “100 Bible Verses, 
“Acts 1:8 represents Christ’s agenda for the duration of history till He returns.  It’s our personal mandate, and every day of our lives must be spent under its ambition and authority.”

So I repeat Acts 1:8:
“ But you shall receive power when the Holy Spirit has come upon you; and you shall be witnesses to Me in Jerusalem, and in all Judea and Samaria and to the end of the earth.”

The mission of each Believer is to share the Good News of salvation in Jesus Christ the Lord!  Thank you Mighty God for Your plan, thank you Jesus for carrying it out and thank you Holy Spirit for Your power to bring it to fruition.  Oh how we love, adore and worship you Holy God.  Amen