The ancient Christian legacy is a set of common beliefs: one God who created heaven and earth, whose Son Jesus was both human and divine and whose death and resurrection (as foretold by Old Testament prophecies) brought salvation. It is a belief held by many modern Christians as well as those of ancient times that the one God of all inspired the sacred writings of the Hebrew scriptures and the New Testament. These beliefs belong to the orthodoxy (which means “right belief”), and the holy books they use and revere are those that survived the conflicts among the many early versions of Christianity. The sacred texts of other unorthodox Christian sects, such as the Gnostics, did not make it into the canon.

Some modern Christians swear that every word in the Bible is the true word of God and that it contains no errors. Yet Biblical scholars note that no original manuscripts of any of the gospels exist. There is no proof that the Apostles wrote them. The gospels that exist today are several generations of texts removed from the authors whose names they bear.

Even fewer fragments and pages of Gnostic texts survived. The Gnostic Gospel of Peter, Secret Gospel of Mark, Dialogue of the Savior, and Egerton Gospel each exist in only a single manuscript, although fragments of the Gospel of Mary survive in both the Coptic and Greek versions (no complete version of that gospel exists). While the entire Gnostic Gospel of Thomas is preserved, it exists only in the Coptic, although three Greek fragments make it likely that it was originally a Greek composition.

Jesus and his Apostles spoke Aramaic, although some scholars say they most likely spoke Hebrew in the synagogue. The first oral stories of Jesus' life and ministry were almost certainly in Aramaic. Paul, a Hellenistic Jew, spoke and wrote Greek, and his letters, the earliest writings of the New Testament, were written in Greek. So what theologians, biblical scholars, and historians have to work from are mostly translated copies or fragments. Some are in Greek, but many are in the Egyptian Coptic language that has been described by some ancient language experts as a kind of shorthand for translating Greek into an Egyptian language with Greek characters. Christian missionaries used the Egyptian Coptic to evangelize Egyptian peasants, so many of the sacred texts they used were translated into that language.

Scholars say there is no evidence that Jesus ever wrote anything for his disciples or for posterity. Some who believe that the New Testament literally contains the word of God sometimes refer to 2 Peter 1:21: “For the prophecy came not in old time by the will of man: but holy men of God spake as they were moved by the Holy Ghost,” and also 2 Timothy 3:16: “All scripture is given by inspiration of God, and is profitable for doctrine, for reproof, for correction, for instruction in righteousness.” While some Christians believe that every word contained in the New Testament is the infallible word of God, others point out that the process of choosing those New Testament texts took centuries. They were chosen amid an ongoing conflict between those who believed the orthodox texts represented Jesus' words and deeds, while others, the Gnostic Christians, were just as certain that orthodox writings had an inferior understanding of the true knowledge Jesus brought. Most modern scholars hold the opinion that Jesus' words and teachings were disseminated orally for decades before others began writing them onto papyrus or in codices (leather-bound books).

As the conflict raged on, the scriptures were translated, copied, recopied, widely circulated, and passed down through generations. Human error accounted for mistranslations, misspellings, and omissions. When mistakes were caught and corrections made, the attempt (for example, words out of sequence) sometimes changed the meaning of the entire sentence.

Scholars say there are even forgeries called pseudepigrapha (“false writings”) that circulated in the ancient world and later appear in the apocrypha and even in the canonical New Testament. The latter has two — the first and second letters of Timothy and Titus (known as the pastoral Epistles). Paul supposedly wrote the letters; however, historians and Biblical scholars say that they were most certainly penned after his death.