Book that tells us about the first people to belong to the christian church?

Acts of the Apostles has long been regarded as a history of the early Church. The Acts Seminar was set up to review the book carefully and look for evidence of historicity in Acts. It determined that the book was written in the second century and does not accurately record events and personalities of the early church. Scholars participating in the Seminar concluded (See Acts and Christian Beginnings) that Acts is "a primary resource for understanding second-century Christianity", as the book writes of events and purported events in the time of Peter and Paul as if they took place at the time of writing.