Acts of the Apostles.
Acts of the Apostles is the New Testament book quite widely thought of as a book of history, covering the actual history of the early Church. However, New Testament scholars see it otherwise. John Dominic Crossan (The Birth of Christianity) says that Acts of the Apostles is theology rather than history.
Burton L. Mack (Who Wrote the New Testament) more bluntly says that Acts of the Apostles marks the shift in focus for second century mythmaking, away from Jesus and towards the apostles, while Uta Ranke-Heinemann (Putting Away Childish Things) says the book is a work of propaganda aimed at Gentile Christians and Gentiles who have not yet become Christians.