Jesus offers us the power to be witnesses, to heal, to proclaim the good news of the kingdom of God, to do good cf. Acts 10:38, Romans 12:21. Acts 1:8 functions as an outline for the Book of Act in that:
1- It encourages us to observe the source behind the boldness of the early Disciples
2- It shows us that the command to witness that Jesus gave started eventually from Jerusalem, Judea, Samaria and has gone across the Earth
3- It teaches us that the other disciples indeed needed the Power of the Spirit of God to make Jesus known cf. Acts 7, Acts 19:1-2
4- It gives us a fuel and burning desire to witness even today’s seeing that evangelism becomes easy when we obey God through the Holy Spirit and cooperate with Him.
We fit in this Acts 1:8 , in that the word of God is alive and this command is also for us today.