Biblical authorship can be a difficult question to answer. Because no original manuscripts exist, each book of the Bible has a long editorial history, and most scholars agree that later editors had a hand in the final form of the books of the Bible. Because many of the biblical texts remain strictly anonymous, scholars often disagree over many of the details related to the authorship, composition, and origins of these writings. In any case, it appears that the early writers of the Bible were concerned less with authorship and more so with the authority of the text. Even though we may not always be able to definitely trace authorship for each book of the Bible, we can rest assured that it does contain the words of God.

Most Protestant Bibles, such as the King James Version, divide the Old Testament into four sections, namely the Law, History, Poetry, and Prophets. Each of these sections, and each of the books in these sections, contain different theories and traditions regarding their authorship.

The Law

Tradition ascribes the first five books of in the Old Testament—Genesis, Exodus, Leviticus, Numbers, and Deuteronomy, together commonly called the Torah or Pentateuch—to Moses, although the texts themselves (except for Deuteronomy) are anonymous. While some of the source material may go back to Moses, many scholars today believe that the Pentateuch consists of several different sources that were combined together and edited over time for several centuries. Scholars point to apparent narrative seams, unnecessary repetitions, and seemingly contradictory details as evidence for this theory.

For most of the 20th century, the predominant model for understanding this process was called the “Documentary Hypothesis,” which posited that there were four main sources, or “documents,” which were combined together to create the Pentateuch. These were commonly referred to as J, E, D, and P—J and E referring, respectively, to the divine names Jehovah and Elohim (the main name for God used in each), D referring to Deuteronomy, and P referring to a Priestly source.

In recent years, many scholars have critiqued this model and a variety of other approaches have emerged. Among the other models are the “Supplementary Hypothesis,” wherein a base text making up the main narrative of the Pentateuch is believed to have been “supplemented” by additional sources over time. Another model is commonly referred to as the “Fragmentary Hypothesis,” which proposes that rather than using sources that already had an overarching narrative, a variety of shorter, more “fragmentary” sources were patched together to form a coherent narrative. Most models for the authorship of the Torah are variations of either the Documentary, Supplementary, or Fragmentary approach, or sometimes a combination of these approaches.

The Histories

The Old Testament has two main narrative histories that tell and contextualize Israel’s history in different ways. The first consists of the books of Joshua, Judges, 1 and 2 Samuel, and 1 and 2 Kings and is often called the “Deuteronomistic History” by scholars, because of its apparent emphasis on the covenant as found in Deuteronomy. The authorship of these books is entirely anonymous, but as with the Pentateuch many scholars believe that multiple sources were used in its composition over time. Since this history ends with the destruction of Jerusalem by the Babylonians, some scholars believe that the main author or editor lived during the Babylonian exile.

The second major narrative history primarily consists of the books of 1 and 2 Chronicles, and this is often called “The Chronicler’s History.” Because Ezra and Nehemiah pick up where Chronicles ends, some scholars also include them as part of the Chronicler’s History, though others have argued that there are certain theological differences which indicate that these books were originally separate from this history. While the text has likely undergone some editing over time, scholars generally believe the books of Chronicles are primarily the work of a single author due to the overall unity of the narrative. The identity of this author is unknown, though some Jewish and Christian traditions attribute it to Ezra. Many scholars believe it was a Levitical priest living in Jerusalem sometime after the Babylonian exile.

The Poetic Books

The poetic books in the Bible range from Job to the Song of Solomon. The narratives of these books, such as Job, are told in poetic form. Once again, the authorship of most of these works is unknown. Tradition identifies David as the author of many of the Psalms; and Proverbs, the Song of Solomon, and possibly Ecclesiastes (although it is anonymous) are often associated with Solomon. Most scholars today, however, believe that books such as Psalms and Proverbs contain compositions from many different authors on a wide variety of topics, some of which may go back to the times of David and Solomon, and were possibly written or complied under their authority.

The Prophets

The authorship of prophetic books, such as Isaiah, Jeremiah, Amos, Zephaniah, etc., is traditionally ascribed to the prophet for whom each book is named, but once again many scholars believe the issue is more complex, with later writers and editors—perhaps disciples of the original prophet—playing a role in compiling, editing, and perhaps at times expanding on the original prophets writings.

The authorship and composition of the book of Isaiah is a particularly complex issue among scholars today. Many scholars believe that it should be divided into two or three main sections, with Isaiah 1–39 generally being attributed to the original Isaiah while Isaiah 40–66 is attributed to one or more later writers, typically referred to as “Deutero-” (Second-) and “Trito-” (Third-) Isaiah. Among the reasons for this, scholars generally point to different writing styles, theological themes, and especially the prophetic emphasis on the Babylonian empire and Judah’s exile, which were in the distant future in Isaiah’s time.

Some scholars have challenged this view, however, arguing that Isaiah is a unified text which largely dates to the period of the original Isaiah, though like other books it may have undergone some later editing.

Latter-day Saint Perspectives

For Latter-day Saints, Restoration scripture provides added perspectives on biblical authorship. For example, while Genesis may have a complex compositional history, including edits and expansions, modern revelation suggests that Moses was indeed the author or original source behind at least some portions of that book (Moses 1:40). Likewise, while later writers may have edited, added to, or revised Isaiah, the Book of Mormon indicates that at least parts of what some attribute to later authors was actually written by the original Isaiah.

Overall, however, Latter-day Saints accept that the Bible is not infallible, and underwent a process of editing over time (AoF 1:8; 1 Nephi 13:28–29). Joseph Smith himself believed the Bible to have been edited by later scribes, and not always for the better. However, not all editorial changes need be seen in a negative light, similar to how Mormon abridged the Book of Mormon from the writings of earlier prophets or like the Teachings of the Presidents of the Church manuals, which are edited compilations of latter-day prophetic teachings. Thus, Latter-day Saints still accept the Bible as inspired scripture.