Beyond its historical account of Paul's journey to Rome, what primary theological theme is emphasized in the book of Acts concerning the spread of Christianity?

A The absolute necessity of adhering to Jewish dietary laws for salvation. B The Holy Spirit's active role in guiding and empowering believers to overcome obstacles and spread the Gospel to diverse people groups. C The importance of establishing a centralized church hierarchy in each city for maintaining doctrinal purity. D The superiority of intellectual arguments and philosophical debates in converting non-believers to Christianity.