Shared ground
Acts starts by explicitly linking itself to an earlier written account for the same addressee, Theophilus. The writer frames that earlier book as covering what Jesus began to do and teach, up to Jesus being “received up,” after giving instructions to the chosen apostles.
The opening also sets the tone for Acts: what follows is presented as the continuation of Jesus’ work, now mediated through apostles who were instructed and later empowered. The writer highlights three anchors for the transition: (1) Jesus’ post-suffering life is presented as publicly knowable, supported by “many proofs,” (2) Jesus’ teaching focus during this period is “God’s kingdom,” and (3) a promised divine gift is imminent and is tied to “baptized in the Holy Spirit” (Spirit), contrasted with John’s water baptism.
Where interpretation differs (only where needed)
Two phrases carry most of the interpretive load.
First, “all that Jesus began to do and to teach” (v.1). Many readers take “began” to imply that Acts will show what Jesus continued to do and teach through his agents. Others hear it more loosely, as a simple way of describing the whole scope of Jesus’ earlier ministry, without stressing a strong “continuation” idea.
Second, “he had given commandment through the Holy Spirit” (v.2). Some think this means the Spirit was the means by which Jesus gave these instructions (divine empowerment or guidance in the moment). Others think it points to the Spirit as the source of the instructions’ authority, or that it summarizes the broader pattern of Jesus acting in step with the Spirit.
Why the disagreement exists
Acts 1:1–5 is a tight bridge between books. It offers summary statements rather than details (it does not list the “proofs,” it does not spell out the promise, and it does not unpack how Spirit-baptism works). Because the wording is compact, readers supply connections from the larger story (especially Luke’s earlier book and the next scenes in Acts).
What this passage clearly contributes
Explicit in the text: the author is continuing a previous account; Jesus’ ascension marks a transition point; the apostles are “chosen”; Jesus’ resurrection life after suffering is asserted and presented as evidenced; there is a defined forty-day period of appearances and teaching about God’s kingdom; and the apostles are told to remain in Jerusalem awaiting a soon-coming “promise of the Father,” described as baptism in the Holy Spirit.
Reasonable inference (but still inference): Acts is likely aiming to show continuity between Jesus’ ministry and the apostolic mission, and to frame the coming events in Jerusalem as the fulfillment of Jesus’ stated promise (see the next step in Acts 1:6).