The gospel spread at the beginning in part because of miracles. But these miracles were signs, pointing to something else: The identity of Jesus, and what He will do for those who repent.

Resources:

Acts 3

Acts: Baker Exegetical Commentary on the New Testament, Darrel Bock

Acts (The NIV Application Commentary)Ajith Fernando

Acts 1-12 For You: Charting the Birth of the Church, Al Mohler

Exalting Jesus in Acts, Tony Merida