Every book. Its author. Its audience.

Job never identifies its own author, and the book itself gives no date for when it was written. Tradition has offered various guesses over the centuries, including Moses, Solomon, or Job himself, but none of these is more than an educated guess, and no consensus has ever formed. The story's patriarchal setting, wealth measured in livestock, no mention of Israel, the law, or a priesthood, leads many scholars to place the events themselves in the patriarchal era, roughly the time of Abraham, even though the book's polished poetry may well have been composed and written down considerably later. Both the author's identity and the book's composition date remain genuinely unknown.

The book never names its author directly; it identifies him only as 'the Preacher' (in Hebrew, Qoheleth), 'son of David, king in Jerusalem,' language long read as pointing to Solomon. Jewish and Christian tradition held to Solomonic authorship for most of the book's history. Since the 19th century, many scholars have argued that the Hebrew text contains vocabulary and grammatical forms that only appear elsewhere in Israel's writing centuries after Solomon's time, suggesting an anonymous later author writing in Solomon's persona as a recognized literary device. Both the traditional and the later-authorship views are held by serious scholars today.

Jewish and Christian tradition has long held that Isaiah wrote the entire book in the 8th century BC. Since the 19th century, a significant strand of critical scholarship has proposed the book combines material from multiple hands across different eras, often labeled First Isaiah (chapters 1-39, 8th century BC), Second Isaiah (chapters 40-55, written during the Babylonian exile), and Third Isaiah (chapters 56-66, written after the return from exile), largely because the historical setting and tone shift partway through the book. This is one of the longest-running authorship debates in Old Testament scholarship, and serious, faithful scholars hold positions on more than one side of it.

The book is anonymous in the Hebrew text itself. The tradition connecting it to Jeremiah goes back at least to the Greek Septuagint translation and to 2 Chronicles 35:25, which mentions Jeremiah composing a lament, though for a different occasion. Most scholars still consider Jeremiah a reasonable candidate given his well-documented grief over Jerusalem elsewhere in his own book, but the attribution to Lamentations specifically is traditional rather than stated in the text.

Jewish and Christian tradition has long held that Daniel, a Jewish exile who rose to high office in Babylon and then Persia, wrote the book in the 6th century BC, describing events he lived through and visions he received. Since the 19th century, a substantial body of critical scholarship has argued the book was actually composed much later, around 165 BC during the Maccabean revolt against the Greek ruler Antiochus IV Epiphanes, on the grounds that its later chapters describe post-Babylonian history in unusually specific detail and that some of its Aramaic and Persian or Greek loanwords fit a later era. This is one of the most significant and long-running dating debates in Old Testament studies, and thoughtful, faithful scholars remain divided on it.

The book is written about Jonah in the third person throughout, including unflattering details of his anger and disobedience that would be unusual for him to record about himself, which leads many scholars, including some who hold to a historical reading of the events, to think it was composed by someone drawing on the tradition of his mission rather than by Jonah directly. A separate and long-running debate concerns genre: whether the book records a literal historical event or is a didactic parable using a known prophet's name. This reference does not take a side on that genre question.

Most of the book's authorship is not seriously disputed. However, a number of scholars have long noted that chapters 9-14 differ noticeably in style, tone, and historical reference from chapters 1-8, leading many to propose they were written later, possibly by a different hand, and appended to Zechariah's original prophecies. This 'two-part Zechariah' question echoes the better-known authorship debate over Isaiah, though it is less prominent and remains unsettled either way in scholarship.

The Gospel itself never names its author internally; the title 'According to Matthew' and the traditional attribution to the apostle and former tax collector come from early church tradition, first attested by the 2nd-century bishop Papias. Most modern critical scholars think the Gospel's author drew on Mark's Gospel as one of his sources, which some find hard to square with an eyewitness apostle relying on a non-eyewitness's account, and so favor an anonymous early Christian writer working in Matthew's circle or tradition. The traditional apostolic attribution remains widely held as well.

The Gospel does not name its author within the text. Early church tradition, again traced to Papias in the early 2nd century, holds that Mark, a companion of Peter mentioned elsewhere in the New Testament, wrote down Peter's preaching and recollections after Peter's death. Most scholars, critical and traditional alike, consider Mark's Gospel the earliest of the four and a likely source for Matthew and Luke, and the Petrine connection is one of the more widely accepted traditional authorship claims among the Gospels.

Luke's Gospel and its sequel, Acts, are formally anonymous, but internal evidence (a shared dedication to 'Theophilus,' consistent style and vocabulary, and firsthand 'we' passages in Acts describing travel with Paul) has long pointed to a single author who was Paul's companion. Early church tradition identifies this companion as Luke the physician, mentioned in Colossians 4:14. Common authorship of Luke-Acts is broadly accepted even among critical scholars; the specific identification of that author as Luke rests on tradition rather than a name in the text itself.

The Gospel refers to its source as 'the disciple whom Jesus loved' without naming him directly, and early church tradition identifies this figure as the Apostle John. This identification was widely held in the early church and remains the majority traditional view. Since the 19th century, some critical scholars have proposed the Gospel instead reflects the teaching of John filtered through a later community or a different author associated with him, largely because of its distinct style and theology compared to the other three Gospels. The apostolic authorship view remains strongly held as well.

The letter names Paul as its author and was accepted as his by the early church without significant challenge for many centuries. Since the 19th century, a number of critical scholars have questioned Pauline authorship, pointing to its distinctive vocabulary and longer sentence structures compared to Paul's undisputed letters, along with some differences in emphasis, and have proposed it was written by a later follower of Paul in his name and tradition. Many other scholars find these stylistic differences reasonably explained by a different secretary, purpose, or occasion, and hold to direct Pauline authorship. Both positions are represented in serious scholarship today.

1 Timothy, 2 Timothy, and Titus are known together as the Pastoral Epistles and share the same authorship question. The letters name Paul as author and were accepted as his throughout most of church history. Since the 19th century, a substantial number of critical scholars have questioned this, pointing to vocabulary rarely or never used in Paul's other letters, a more developed church leadership structure than his earlier letters describe, and a writing style some find different enough to suggest a later follower of Paul wrote in his name, drawing on genuine Pauline tradition. Many other scholars find these differences explained by the letters' distinct purpose (practical instructions to individual co-workers rather than to churches), a later stage in Paul's ministry, and possibly a different secretary, and continue to hold direct Pauline authorship. Both views are actively represented in scholarship.

Shares the same Pastoral Epistles authorship question described under 1 Timothy: traditionally Pauline, with a body of critical scholarship proposing a later follower of Paul as the actual author. 2 Timothy's intensely personal, farewell tone is sometimes cited by defenders of Pauline authorship as harder to explain as a later imitation.

Shares the same Pastoral Epistles authorship question described under 1 Timothy.

The author's identity was already unknown to the earliest church. The third-century scholar Origen concluded that who wrote the epistle, only God knows the truth. Paul, Barnabas, Apollos, Luke, and Priscilla have all been proposed as candidates over the centuries based on style, theology, and internal clues, but none has ever achieved consensus, and no serious scholar treats any candidate as certain.

Several men named James appear in the New Testament, and the letter identifies its author only as 'James, a servant of God and of the Lord Jesus Christ,' without further clarification. Tradition has long understood this to be James the brother of Jesus, who led the Jerusalem church (Acts 15, Galatians 1-2), rather than either of the two apostles also named James. Some critical scholars question this identification and propose a later, unknown author writing under his name, citing the letter's polished Greek style as unusual for a Galilean tradesman's brother, though others note James could plausibly have used a skilled scribe, as was common practice at the time.

The letter names Peter as its author and states it was written 'through Silvanus' (5:12), likely meaning Silvanus served as his secretary or letter-carrier. Most scholars, traditional and critical alike, find this a reasonable explanation for the letter's polished Greek, which some had otherwise thought unusual for a Galilean fisherman; a minority of critical scholars still favor a later author writing in Peter's name, citing the letter's apparent awareness of organized persecution some think developed only after Peter's likely death.

2 Peter is widely regarded as the most disputed book in the New Testament in terms of authorship. It was among the last books accepted into the New Testament canon, and even early church figures such as Origen and Eusebius noted doubts about it in the 3rd and 4th centuries. Its Greek style differs noticeably from 1 Peter, and it shares extensive material with the letter of Jude, raising questions about which came first and how the overlap arose. A large body of critical scholarship holds it was written by a later author in Peter's name, a practice with precedent in the ancient world, while others defend direct or substantially Petrine authorship, sometimes proposing a different secretary than the one used for 1 Peter. This reference notes the dispute honestly rather than resolving it.

Like the Gospel of John, this letter never names its author. Its close stylistic and theological similarity to the Fourth Gospel has long led scholars, both traditional and critical, to treat the two as coming from the same hand or circle, whichever view one takes on who that was.

The letter identifies its author only as 'the elder,' not by name. Tradition holds this is the Apostle John, consistent with 1 John and the Gospel of John. Some scholars, noting the early church historian Eusebius' reference to a separate figure called 'John the Elder' distinct from the apostle, have proposed this shorter letter came from that figure instead. The question turns entirely on the meaning of the letter's own self-description and remains unresolved either way.

Shares the same 'the elder' authorship question described under 2 John.

The letter identifies its author simply as 'Jude...a brother of James,' widely understood to mean the James who led the Jerusalem church, and thus Jude, another of Jesus' half-brothers named in the Gospels. The letter shares extensive material with 2 Peter, and quotes directly from two Jewish writings outside the Old Testament canon (1 Enoch and, likely, the Assumption of Moses), which has drawn scholarly discussion, though quoting a source does not necessarily mean treating it as Scripture. A minority of scholars propose a later author writing under Jude's name; most find no strong reason to doubt the traditional attribution.

The book names its author simply as 'John' without further identification, and early church tradition widely identified him with the Apostle John. As early as the 3rd century, the Alexandrian bishop Dionysius observed that Revelation's Greek style and vocabulary differ noticeably from the Gospel and letters of John, and argued for a different author of the same name, a view some modern scholars share, sometimes proposing 'John the Elder' or another early Christian prophet named John. Others attribute the stylistic differences to genre, since apocalyptic literature has its own conventions, and to the author's evident fluency in Hebrew-influenced Greek, and hold to apostolic authorship. Both views remain represented in scholarship today.