Book dedications were common among the Greeks. Luke had dedicated his Gospel to his Greek-speaking friend Theophilus (Luke 1:3). He continues his contact with Theophilus to complete the story from the birth of Christ to the establishment of the church all around the Mediterranean world. Immediately he emphasizes key ideas of his book: the command to witness; the role of the apostles; the significance of the Holy Spirit; and his literary launching pad, the ascension of the Lord. Luke connects Acts to his Gospel with the simple words, after his suffering. He refused to point to the resurrected, glorious, ascended Lord without pointing to the suffering Servant.

With that connection to the Lucan gospel, we see him begin the book in a way that reminds us that while Jesus had died in the crucifixion, he had shown himself in the 40 days since the resurrection to his disciples so that they might know that he was alive. He did these appearances so that they might be assured of his life-post-death.
And it would take a few times for people to become more and more comfortable with the idea of resurrection. As you know, there were many in the Jewish tradition who did not see resurrection as something that was even plausible, let alone reasonable to consider. While the disciples were by and large not from that school of theological thought, it would have been around them and so the idea of resurrection would have taken a few times to really take hold.
During the forty days that separated the resurrection and the ascension, Jesus further taught the disciples, preparing them to lead the early church. This is the only New Testament reference to these post resurrection days. You will probably find it helpful to read at least the last chapter of Luke to get a feel for how Luke makes the transition into this second letter to Theophilus. To lead, they first had to be convinced that death had turned to life. During this time he gave many convincing proofs that he was alive … and spoke about the kingdom of God.
His knowledge of the kingdom of God was made that more clear through his time in the grave. Jesus spoke of it clearly, as if it was a place he had spent time, made a home, and was now clearly the king of. He had been given all authority in that kingdom, and he continues to reign in that kingdom today.

1. If you knew you only had a few days left to tell your friends and family everything important, what would you tell them first? 
2. If you could give one piece of advice, what would it be? 
3. Do you think Jesus knew that he was on a shortened timeline once he was resurrected?