Since the early days of the church, it has been widely acknowledged that Luke is the author of Acts, even though he does not refer to himself by name. Theophilus, on the other hand, was most likely a wealthy believer who may have supported Luke financially during his research for the book. Luke's Gospel tells the story of Jesus' teachings and actions until the day he went up into heaven. The book emphasizes the importance of the Holy Spirit, as Jesus gave commands through it to his chosen followers. This idea of God choosing people to spread the news of salvation is a recurring theme in the book. After his resurrection, Jesus spends forty days with his disciples, teaching and preparing them for the upcoming ministry.

The Apostolic ministry is based on the first-hand accounts of the disciples. When selecting a replacement for Judas, Peter requires the candidate to have been with them throughout Jesus' ministry, from the time of His baptism by John until His ascension. This is to ensure that the new member can testify to the resurrection of Jesus. Jesus' resurrection resulted in a physical body that transcends ordinary, mortal existence and is not limited by physical obstacles, yet remains a real and physical body. After the resurrection, Jesus became the leader of a new, changed, and everlasting human race. Based on this, the disciples receive their mission from Jesus, who is now the resurrected King. As in the Gospels, the kingdom of God refers to the Lord's rule and reign. This kingdom is not localized with borders or made up of particular people connected politically, culturally, or ethnically but is established in the lives of men and women through the power of the Gospel. Luke depicts the kingdom that will be revealed as limitless in time and space when the King returns, and those who believe in the message will enter it.

Jesus instructed his disciples to remain in Jerusalem and wait for the Holy Spirit to come, which was promised by John the Baptist. According to the Gospel of Luke, John said that Jesus would be the one to baptize with the Spirit. Therefore, the "baptism" of the Spirit refers to the giving of the Spirit by Jesus after his resurrection and ascension rather than a separate second blessing or gift given to those who have already received him. The main message of Acts is that Jesus rose from the dead, and the disciples were witnesses of this event. The Spirit empowered them to share this message. Acts is about the resurrection, witness, and Spirit. The disciples wonder when the kingdom will be established and hope for a significant event. However, Jesus shifts their focus to the current state after his resurrection. He explains that the kingdom is being restored and will continue with the arrival of the promised Holy Spirit, who will guide and strengthen them. The restoration process has already started.

After Jesus ascends, the disciples gaze up and continue to do so. They have just witnessed an extraordinary event that surpasses anything they have ever seen or will see again— not even the departures of Enoch or Elijah could compare. Therefore, angels appear and ask why they are staring at the sky: "Men of Galilee, why do you stand looking into heaven? This Jesus, who was taken up from you into heaven, will come in the same way as you saw him go into heaven" (v. 11). Jesus ascended to heaven to be with the Father. This event created a way from the earthly realm to the heavenly realm. Although we do not know how Jesus made this journey, the Bible describes heaven as God's dwelling place, which will ultimately be merged with a new earth. The main point is that heaven is where Jesus, the divine King, reigns with finality and authority over his kingdom work on earth. According to verse 12, the ascension occurred on the Mount of Olives, also known as "the mount called Olivet." Luke mentions that this location was a "Sabbath day's journey" away from Jerusalem, a distance of a little over half a mile allowed to be traveled on the Sabbath according to Jewish tradition.

Matthias was chosen to replace Judas after prayer, devotion, and waiting on God. The decision was not deemed incorrect and paved the way for the fulfillment of Scripture, Jesus' promise, and the coming of the future kingdom through the Spirit at Pentecost. This ensured that eyewitnesses were present before witnessing began.

In Acts 2, Jews in Jerusalem are still celebrating Pentecost, but this Pentecost is different. It is the last Pentecost. Passover is fulfilled, and now it is time for the fulfillment of Pentecost. The description of the event is not precisely a natural occurrence but rather likened to one. It is an effort to express supernatural visions and experiences that were real and happened but are indescribable in their entirety. In this instance, it resembled a strong gust of wind. The meaning of fire in Acts 2 is straightforward. It can be compared to similar references in the Bible, such as the burning bush from which the Lord appeared to Moses or the pillar of fire that guided the Israelites during their journey in the desert. It is also possible that the fire signifies the purification of the prophet Isaiah's tongue with a burning coal, as described in Isaiah 6:4-7. In Acts 2, God's presence is accompanied by an action that confirms it. The sound comes from heaven, known as God's dwelling place. This event marks another intersection between heaven and earth following Jesus' ascension. Now, the Spirit from heaven fills the apostles for witnessing on earth. Being "filled with the Holy Spirit" enables one to serve with empowerment, typically proclaiming or undertaking a mission. In Acts, the Spirit's role in salvation is of utmost importance - receiving the Spirit is the primary reason why Gentiles should be baptized and considered full members of the new covenant (15:8-9). However, on the day of Pentecost specifically, the disciples are empowered with the Spirit to undertake the significant task ahead.

The tongues at Pentecost were actual languages, indicating that the miracle was related to speaking rather than hearing. While the Holy Spirit enabled the disciples to speak, there is no evidence that the Spirit enabled them to hear similarly. Throughout the book of Acts, the Spirit empowers believers to serve in various ways. The population of Jerusalem would increase significantly during major Jewish feasts, sometimes doubling or tripling in size. Pilgrims across the Mediterranean region would join those living in Jerusalem and Judea to participate in the feasts. The speaker's origin is also a factor. Although not everyone knows the speakers' origin, some can identify them. This leads to word-of-mouth spreading, revealing that the speakers are from Galilee (2:7). What's surprising is that these individuals, who typically speak Aramaic and Greek, suddenly speak various other languages and dialects. This is where the fulfillment of the promise made to Abraham (Gen. 12:1-3) starts along with the means to fulfill it. The gathering of nations takes place, and each hears about the "mighty works of God" (Acts 2:11) in their language. In verse 13, they accuse the people of being drunk. The events of this day are unprecedented and cannot be compared to anything from history. The astonishing nature of what has happened makes it difficult to describe using a common language.