Acts 1:8 – “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.”.”
Jesus is about to unleash His disciples to take the message of the Gospel to the ends of the earth. This is an important work. It is an urgent work. However, He does not want them to start just yet. - Acts 1:4 says, "And while staying with them he ordered them not to depart from Jerusalem, but to wait for the promise of the Father."
The disciples could have gone out and preached Jesus. But they would have failed. Not because they did not have the Spirit. This is not the first time that the disciples will encounter the Holy Spirit. In John 20:22, Jesus breathes on the disciples and says "receive the Spirit." In other words, coming into Acts 1, the disciples do have the Holy Spirit in them. But there is a difference between them having the Spirit and the Spirit coming upon them. To "come upon" means to "overtake."
So, even though the disciples has the Spirit in them after John 20, by Acts 1, they are still not ready to go into all the world. They needed to wait for the power of the Spirit to come upon them. How often do we rush out to do work for Jesus assuming that, since the Holy Spirit is in us as believers, the power of the Holy Spirit has not "come upon" us?
Would you open your heart afresh to the anointing power of God's Spirit upon you? Would you pray for this power to come upon your church?