The answer is: Luke

Luke 1:3 / Acts 1:1 - From these two verses it is reasonable to assume Luke wrote Acts.

The author of Acts is commonly identified as Luke, who also penned the Gospel of Luke. Interesting tidbit: both books are specifically addressed to a figure named Theophilus, which raises a fun mystery—who exactly was Theophilus? Some scholars think he could have been a high-ranking official or simply a benefactor of Luke’s work, hoping to gain more insight into early Christianity.

Luke's Greek is also noteworthy, as he appears to have been well-educated and had a medical background—anyone who reads Acts can see the detailed narratives and charitable accounts that may reflect his keen observational skills. What's fascinating about Acts is how it spans a transition from a small, localized movement within Judaism to a bold proclamation of faith in the Mediterranean world.

Let’s not forget the echoes of the Old Testament that resonate throughout both Luke and Acts. The role of the Holy Spirit in guiding the apostles connects with spirit motifs found throughout biblical history. For instance, the flame that appeared at Pentecost reflects God’s fiery presence at Mount Sinai and hints at a new community born from powerful divine inspiration.

Moreover, Luke hints at making a point to place marginalized individuals at the heart of his narratives, showcasing the shift from exclusion to inclusion in early Christian communities. There’s a broader truth laid here for anyone who reads Acts: the message transcends boundaries and cultures, telling us that hope for a brighter world isn't bound by who we are but by the spirit of what we can become together.