The key to the apostles" successful fulfillment of Jesus" commission was their baptism with and consequent indwelling by the Holy Spirit. Without this divine enablement they would only have been able to follow Jesus" example, but with it Jesus could literally continue to do His work and teach His words through them. Consequently their preparation for the baptism of the Spirit was very important. Luke recorded it to highlight its foundational significance. [source][source][source]Acts 1:6-8 announce the theme of Acts and set the stage for all that follows. [source][source][source]
"The concept of "witness" is so prominent in Acts (the word in its various forms appears some thirty-nine times) that everything else in the book should probably be seen as subsumed under it-even the primitive kerygma [1] ..." [2][source]