The document is a handbook titled 'Essential Christianity' by Walter Martin, which provides an introductory overview of fundamental Christian doctrines. It emphasizes the importance of the Bible as the authoritative word of God and discusses concepts such as the inspiration of scripture, the nature of Jesus Christ, and interpretations of salvation. The author aims to clarify Christian theology for both believers and non-believers while highlighting the necessity of a faith-based union with Christ for true understanding and redemption.