the book narrates how the resurrected jesus makes the apostles his witnesses, and instructs them to convert all peoples to the ends of the earth (). through the holy spirit, god then empowers the apostles in their missionary work, with the ability to perform miracles such as healing the sick, casting out demons and raising the dead, while spreading jesus' gospel. problems such as anti-christian persecutions, and conflicts about whether converts should first become jewish before they can become christians, are overcome.