The answer is: Luke

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

The book of Acts weaves a thrilling narrative detailing the spread of early Christianity after Jesus' resurrection. Authored by Luke, a physician, this text serves not only as a continuation of his gospel but also as an impressive account of the Apostles' adventures. Interestingly, Luke takes an almost cinematic approach—painting vivid characters and remarkable happenings that bring the good news of Christ from Jerusalem to "the ends of the earth," capturing the urgent and adventurous spirit of the early believers.

Did you know that among the four Gospels, Luke’s is the only one that tells the story of the prodigal son and the Good Samaritan? This reflects his deep commitment to showcasing themes of compassion and inclusion—a theme that continues throughout Acts. Characteristically, the book emphasizes the unity of believers regardless of their diverse backgrounds.

And here's an intriguing nugget: Despite his brilliance in storytelling and focus on the goodness in humanity, the author is behind the scenes. Little is known about Luke; even during his time, he remained relatively anonymous, a point that reinforces the transparency of the Gospel’s message rather than the aura of its writer.

Acts culminates splendidly in Paul's dramatic conversion, marking a significant pivot in Christian history where the message goes beyond cultural constraints and engulfs the Gentiles. Each story in this book reminds us we’re part of an ongoing journey—just like those early followers of Christ spreading hope amidst challenges.