1 The former account I made, O Theophilus, of all that Jesus began both to do and teach, 2 until the day in which He was taken up, after He through the Holy Spirit had given commandments to the apostles whom He had chosen, 3 to whom He also presented Himself alive after His suffering by many infallible proofs, being seen by them during forty days and speaking of the things pertaining to the kingdom of God.
We don't know if Theophilus is a person or a term for all believers (Theo Phileo - brothers of God).
What we do know is that Luke begins both of his books this way. Either way it makes no difference. The point is that Luke set out first to write down a detailed account of Jesus' life from birth to death and resurrection. Now he is writing a second book to tell "Theophilus" what happened after Jesus rose and appeared to the disciples/apostles several times with many infallible proofs.
The main thrust is that there is no doubt at all that Jesus is alive. For forty days He visited them. He had one topic on His mind - the kingdom of God. Why that topic? Because it was the central misunderstanding. The disciples had been raised with all Jews to believe that the kingdom of God was a place ruled by a king. It was not. It was a matter of the mind. It was a character issue. It was a Divine perspective.
In the kingdom of men certain people have more value and importance than others. In the kingdom of God all are equal. In the kingdom of men the strong rule over the weak. In the kingdom of God love serves all in need. In the kingdom of men the goal is to get to the top and be served by those at the bottom. In the kingdom of God the entire hierarchy is reversed. The greatest are those who live to serve others.
Jesus came to model the kingdom. He had no place to lay His head. He owned nothing. He strived for nothing but to be a servant to Jews and Samaritans and even those in Tyre and Sidon and Decapolis. Borders meant nothing to Him. Social constructs meant nothing to Him. From prostitutes to people of 'power', He treated them all the same. The disciples were confused by it. Sometimes they argued with Him about it. None of that changed His behaviour. He was setting up a kingdom that couldn't be seen with the eye but could be felt with the heart.
In the kingdom of men when you fail miserably you are cast aside. In the kingdom of God you are offered healing and restoration. The forty days Jesus spent with the eleven were used primarily to love them back into service. They needed to understand they were not being cast aside.
The kingdom of God is so radically different that 2000 years later we are still having a hard time seeing it and believing it.
Love conquers all. Love serves. Love forgives. Love restores. Love wins.