“But you will receive power when the Holy Spirit has come upon you, and you will be my witnesses in Jerusalem and in all Judea and Samaria, and to the end of the earth” (Acts 1:8 ESV).
In a sense, the mission is accomplished. When Jesus said, “It is finished,” in John 19:30, the work of salvation was accomplished. But sharing that work with all the world is not yet finished. There is still a mission to accomplish, which is why Jesus promised to send the Holy Spirit to believers in Acts 1:8.
Every promise has a purpose. The promise in Jesus’ words before His ascension is that believers will have God’s power working on and through them. The battle belongs to the Lord and He works through us. Jesus promises His Spirit to His followers so that they will have His power to do His work. That is the purpose for the promise of the Holy Spirit. Believers are called to share the good news of the Gospel everywhere they go, from Jerusalem to the end of the earth. His power is given so that His mission can be accomplished.
The promise of the Holy Spirit requires believers to lean on His power and wisdom. Do not try to spiritual work with fleshly power. Pray and work in the strength God gives. Look for opportunities to share Jesus with others. Be bold, in the Spirit’s strength, to mention His Name and to proclaim His Kingdom. He promises His power to do it. There is a mission to accomplish, and it is an impossible mission without Him.