According to the testimony of the New Testament authors, Jesus was born of a virgin woman named Mary as a result of the work of the Holy Spirit. He was raised by His mother and His earthly father, Joseph. Scripture is clear that Mary remained a virgin until Jesus was born (Matthew 1:25). But did Mary have children with Joseph through sexual relations after Jesus was born? Did Jesus have any earthly siblings?
There are two primary positions on this matter. The Catholic Church claims that Mary did not have any other children and therefore that Jesus did not have any siblings. Protestant Christians claim that Mary did have other children and that Jesus did have earthly siblings. In order to determine which position is right, we will need to analyze both Scripture and tradition. First, we will analyze the pertinent verses throughout Scripture. Then, we will look at the history behind the Catholic position and any potential problems with it.
Verses About Jesus’ Earthly Family
Matthew, Mark, Luke, John, Acts, 1 Corinthians, and Galatians all mention Jesus having earthly siblings. Here is a sampling of verses to consider:
Matthew 13:55-56 – “Is this not the carpenter’s son? Is not His mother called Mary, and His brothers, James and Joseph and Simon and Judas? And His sisters, are they not all with us?”
John 7:5 – For not even His brothers were believing in Him.
Acts 1:14 – These all with one mind were continually devoting themselves to prayer, along with the women, and Mary the mother of Jesus, and with His brothers.
1 Corinthians 9:5 – Do we not have a right to take along a believing wife, even as the rest of the apostles and the brothers of the Lord and Cephas?
The History Behind the Catholic Position
Catholics appeal to the extrabiblical account of the Protoevangelium (Protogospel) of James to provide their primary support for what they have deemed the “perpetual virginity” of Mary. This doctrine essentially means that Mary was an ever-virgin, that she never had sex with a man before, during, or after her pregnancy with Jesus. They claim that this is important because it symbolizes Mary’s complete devotion to Jesus.
They also point to the Fifth Ecumenical Council of Constantinople in the year 553 as the church taking its stand on the matter. At this council, the members declared that anyone who believed that the “ever-virgin Mary is called God-bearer by misuse of language and not truly, or by analogy, believing that only a mere man was born of her and that God the Word was not incarnate of her”  was to be accursed. In the Lateran Council of 649, a pope by the name of Martin I condemned those who refused to affirm Mary as “ever virgin and immaculate.” 
Problems With the Catholic Idea of Perpetual Virginity
The primary source that the Catholic Church uses to support its doctrine of the perpetual virginity of Mary is an unbiblical account. This Protoevangelium of James claims that the siblings mentioned in the many accounts of Scripture are actually the children of Joseph from a previous marriage. But this is an unreliable source for many reasons. 
The author of this work is supposedly James, the (according to the Protoevangelium of James) stepbrother of Jesus. But scholars agree that this work wasn’t written until the middle of the second century. James, the brother of Jesus, died in the 60s AD. He couldn’t have written this work. Further, this work contradicts the basic storyline of the birth of Jesus according to the gospels. It was rejected from the canon for good reason. It is not the inspired Word of God, and it should not be the source of any Christian doctrine.
Another problem with the Catholic position of the perpetual virginity of Mary is the fact that the Fifth Ecumenical Council of Constantinople in 553 was not meeting to make an official ruling on the virginity of Mary. They were meeting to make an official ruling on a heresy known as Nestorianism. Nestorius was a bishop who taught that Jesus did not have human and divine natures united together in His person. He had many followers who had adopted this view of the disunity of the Christ. When the council met, they condemned this as heresy and ruled that Jesus was born of the virgin Mary as God Incarnate.
It is unwise to base an entire doctrine on an extrabiblical source that runs in clear contrast to Scripture. It is also wise to base an entire doctrine on the ruling of a council that was not meeting for the purpose of discussing that doctrine. Moreover, it is unwise to base an entire doctrine on speculation that disregards the clear evidence of Scripture.
The Bible issues a clear warning to us not to add or subtract from the Word of God. This command comes at the beginning, middle, and end of God’s Revelation to us (Deuteronomy 4:2, Psalm 30:5-6, Revelation 22:18-19). But the Catholic Church’s denial of Jesus having siblings does just this. There really is no solid base from which the Catholic doctrine of the perpetual virginity of Mary emerges.
Conclusion
The most straightforward and commonsense interpretation of the abundant scriptural evidence is to conclude that Jesus literally had brothers and sisters. Any other understanding is simply an invention of humans that has no biblical basis whatsoever. The matter comes down to whether you want to believe what God revealed in His Word or if you want to believe the fabrication of a fallen human being.
In light of all of the evidence, it is clear that Jesus did have earthly (half) siblings. We even know the names of several of them! Jesus’ brothers were James, Joseph, Simon, and Judas (Matthew 13:55). And we know that Jesus had at least two sisters (note, the plural “sisters” in Matthew 13:56). In all of the ups and downs that this would have included, we can be confident that our Lord knew exactly what it was like to grow up with brothers and sisters.