The debate over whether Jesus of Nazareth had biological siblings is one of the longest running in the history of biblical studies and church history. This has been a matter of debate in theological traditions for centuries, but lexical semantics and linguistic evidence provide the way forward. In order to understand what the ancient authors meant when they referred to the brothers and sisters of Jesus we need to look at the primary lexicographical authority for New Testament Greek, the Bauer Arndt Gingrich Danker Greek English Lexicon of the New Testament and Other Early Christian Literature, commonly known as BDAG.
By examining the entry for ἀδελφός in BDAG we can analyze the exact semantic range of the word, evaluate historical counterarguments, and show that the New Testament writers used ἀδελφός to indicate that Jesus had real siblings born of the same mother.
Knowing the Basic Definition of Lexical.
In historical linguistics the fundamental sense of any word is to be derived from its present-day use in modern literature. The primary definitional entry in BDAG for ἀδελφός is simple and clear. The lexicon describes the word as a male of the same womb as the person in question, brother (Arndt et al., 2000, p. 18).
This basic definition is based on the etymology of the word itself. The Greek word for brother, ἀδελφός, is historically derived from the copulative prefix “alpha” and “delphys,” meaning “womb.” Thus, the etymological root of ἀδελφός literally means someone from the very same womb. This primary sense is referred to by BDAG as being present throughout the great span of Classical and Hellenistic Greek literature from Homer on (Arndt et al., 2000, p. 18).
When New Testament writers like Matthew, Mark, John, Luke and Paul used this expression, it would be understood by their natural audience in its normal, literal sense, unless contextual markers suggested otherwise. This primary meaning accounts for the listing of many foundational passages in the Gospels by BDAG (e.g., Matt 1:2; Matt 4:18; John 1:41; Arndt et al., 2000, p. 18).
Shattering the Cousin Argument
A major argument against Jesus having biological siblings is that ἀδελφός was often used to mean cousin or extended relative in ancient Jewish and Christian contexts. The usual argument of the advocates of this view is that the Hebrew word ach, in the Old Testament, may be used of a wider circle of male kinsmen, and that the Septuagint translated ach by ἀδελφός.
BDAG, however, directly contradicts and disconfirms this. Passages such as Genesis 13:8, Genesis 14:14, Genesis 24:48, Genesis 29:12, Leviticus 10:4, and First Chronicles 9:6 do not establish the meaning cousin for ἀδελφός (Arndt et al., 2000, p. 18). However, the lexicon states that these passages in the Septuagint simply show that ἀδελφός is used rather loosely in isolated cases to refer to masculine relatives of various degrees in the translation of the Hebrew word ach (Arndt et al., 2000, p. 18).
This is an important distinction for proper exegesis. The fact that a Greek translator of ancient Hebrew texts at times used ἀδελφός loosely to represent an elastic Hebrew term does not mean that ἀδελφός contained naturally the standard definition of cousin in original Greek compositions. The New Testament writers who worked directly in Koine Greek were not encumbered with the mechanical translation work from Hebrew originals. If the New Testament writers intended to convey that Jesus had cousins, rather than uterine brothers, Greek had a specific and common word for cousin, ἀνεψιός (anepsios), as in Colossians 4:10. The intentional use of ἀδελφός instead of ἀνεψιός to describe Jesus’s family is a strong argument for the literal meaning of biological brotherhood.
Jesus’ Brothers in the New Testament
BDAG specifically includes the NT references to the brothers of Jesus under the primary definition of biological siblings from the same womb. The following key texts are connected to this main heading: Of Jesus brothers… Matthew 12:46f; 13:55; Mark 3:31f; John 2:12; 7:3, 5; Acts 1:14; First Corinthians 9:5 (Arndt et al., 2000, p. 18).
Let us look at what these specific passages say in their historical and narrative settings.
The townspeople of Nazareth are amazed at Jesus’s teaching and say: Is not this the carpenter’s son? (Matt. 13:55). His mother is not named Mary? Are not his brothers James and Joseph and Simon and Judas? Here we see the crowd naming Jesus’ earthly father figure, his mother Mary and his individual brothers as a familiar, immediate nuclear family unit.
In John 2:12 after the wedding at Cana, the text says the following: After this he went down to Capernaum, he and his mother and his brothers and his disciples. The story clearly distinguishes between the two groups who follow Jesus: biological family (mother and brothers) and spiritual followers (disciples).
Mark 3:31–35 Jesus’s mother and brothers come outside where Jesus is teaching. Jesus is told that his family is looking for him , and he uses the literal family bond to make a spiritual metaphor by asking who his true mother and brothers are. The power of Jesus’s statement rests entirely on the contrast between his literal, natural family waiting outside and his metaphorical, spiritual family seated before him.
In First Corinthians 9:5, the Apostle Paul speaks of the rights of apostles, saying, “Do we not have the right to take a believing wife along with us, as do the other apostles and the Lord’s brothers and Cephas?” In this passage Paul is referring to a particular group of early Christian leaders known as the brothers of the Lord, distinct from both the twelve apostles and Peter.
James the Brother of Jesus
The New Testament tells us that Jesus had several brothers. James was a major figure in the early church. BDAG cites Galatians 1:19 as an instance of this relation, listing James ὁ ἀδελφὸς τοῦ κυρίου (Arndt et al., 2000, p. 18).
Paul refers to his visit to Jerusalem in Galatians 1:19: But none of the other apostles did I see except James the Lord’s brother. Paul’s personal knowledge of James and his explicit designation of him as the brother of the Lord provide first-hand historical testimony from the first century. Paul distinguishes James on the basis of his unique biological relationship to Jesus, a title which was universally accepted in the church in Jerusalem, and later affirmed by non-Christian first century historians such as Flavius Josephus in his Antiquities of the Jews.
Plural Forms & Family Environment
BDAG also discusses the broader semantic capabilities of the plural form ἀδελφοί (adelphoi). The entry notes that in various Greek literatures the plural can mean brothers and sisters, with classical and papyrological evidence, such as Euripides, Andocides, and ancient papyri, such as POxy 713 (Arndt et al., 2000, p. 18). Also, BDAG points out there are passages where ἀδελφοί means brothers and sisters in whatever order the writer desires, citing Polybius, Epictetus, and papyri such as PMich 214 (Arndt et al., 2000, p. 18).
This linguistic fact shows that when the New Testament writers spoke of the ἀδελφοί of Jesus or referred to his sisters (ἀδελφαί, adelphai, e.g., Matthew 13:56 and Mark 6:3), they were referring to a mixed group of siblings, both brothers and sisters, in the home of Mary and Joseph.
The Lexical End Point
Seen from the perspective of Greek lexicography and the historical setting of the first century in an objective way, the BDAG entry for ἀδελφός strongly suggests that Jesus had biological half-siblings born to Mary and Joseph.
- The principal meaning of ἀδελφός is a brother of the same womb.
- The isolated Old Testament translations of the Hebrew word ach do not establish cousin as the default meaning of ἀδελφός in the original Greek of the New Testament.
- The New Testament authors always speak of Jesus’ mother and brothers as one nuclear family, but they use a different language for cousins and spiritual followers.
- Key primary historical sources, like Paul’s own eyewitness account in Galatians, clearly identify leaders like James as the biological brother of the Lord.
There is clear evidence that when the New Testament text is read in its natural linguistic context the ancient authors intended to convey that Jesus lived as the oldest child in a household with brothers and sisters.
References
Arndt, W., Danker, F. W., Bauer, W., & Gingrich, F. W. (2000). A Greek-English Lexicon of the New Testament and Other Early Christian Literature (3rd ed.). University of Chicago Press.
M.J. Kelley II