The Word of God, which consists of the Scriptures of the Old and New Testaments, is the only true guide for faith in God and obedience to Him. The Scriptures principally teach two things: what man is to believe concerning God, and what duty God requires of man. The Scriptures teach that this God is "Triune," which means that He is composed of three persons who are the Father, the Son, and the Holy Spirit. These three persons are one God, the same in substance, and equal in power and glory.
Both the Old and New Testaments of the Bible record and prove what God does in history to save His people from the consequences of their sins. By means of types, ceremonies and prophecies, inspired writers of the Old Testament looked forward to and revealed the unique attributes of a promised Messiah, which means "savior or liberator." These inspired writings concerning the anticipated Messiah and his coming kingdom proclaimed the good news or "gospel" throughout the Old Testament.
The New Testament describes the long-awaited revelation of Jesus as the Messiah (or "the Christ" in Greek). Jesus proclaimed the good news that the Kingdom of God had come to the earth through him. He preached that people could only see this kingdom if they were "born again" (regenerated) by the Spirit of God, which then would free them from the inherent power of sin over them as part of the human race, cause them to believe in Jesus as the Christ, the Son of God, and enable them to live according to the way taught by the Holy Scriptures.