There are numerous reasons why Mary did not continue to be a virgin. In Luke 2:7 “And she brought forth her first born son.” This statement alone does not verify she had other children but if one looks at the whole body of evidence in the Scriptures it seems to be without question.

Notice the phrase- did not “know her.” This phrase to know is almost unanimously used in the Bible in reference to sexual union. In the context it is used, it can only mean this. In Luke 1:34 we have the same phrase in reverse. Mary says to the angel in her response to her bringing forth a child, “how can this be since I do not know a man.” Mary is bewildered, how can she become pregnant without knowing a man. Did Mary know a man, of course she did, she was engaged to be married to Joseph. Did Joseph know Mary, of course he did, but not in the sense of sexual union, this all occurs afterwards. This same term to know is used in Gen.4:1 “ Now Adam knew his wife, and she conceived.” Gen 4:1 Adam meuo his wife, he knew her experientially, intimately (as in sexual intercourse). Clearly this is consistent with the rest of Scripture when used in the same context.

In Luke 1:38 Mary says let it be according to your word” Mary believed without understanding how this is possible. Zacharias said the same thing to the angel about John except his statement was in disbelief. For this she is to be commended as a role model as one in submission to the will of God by faith.

“Joseph did not know her until she brought forth her firstborn son.” The word until in Mt.1:25 is used when the state of things does not change 'until “meaning after the time indicated. Time elapsed and they enjoyed their marriage together like anyone else having more children. This word is common in other scriptures in the same manner, 1 Tim.4:13: “Until I come give attention to reading, until the kingdom of God comes.

Mary having a sexual relationship with her husband does not demean her nor take away the miracle of her being a virgin and giving birth to the Messiah. She was fulfilling the role of a wife, Marriage is blessed by God. At that time in the Jewish culture the more children one had the more God was blessing. Mary endured a life of shame, she lived among indecent people who mocked her accusing her of fornication. She exhibited character and godly qualities, it’s no wonder God chose her to present to the world “Emmanuel” God with us. Mary was given a place as the greatest among women. Paul instructs believers “The husband should give to his wife her conjugal rights, and likewise the wife her husband. For the wife does not rule over her own body, but the husband does; likewise the husband does not rule over his own body, but the wife does. Do not refuse each other except perhaps for a season, that you may devote yourselves to prayer; but then come together again, lest Satan tempt you through lack of self control (1 Cor.7:3-5) It is against all that was in the Jewish culture for Mary not to have consummated the marriage as God had instructed. In Hebrew culture their needed to be a consummation of the marriage for it to be complete. An unconsummated marriage was not recognized under law, in other words it would not be considered a marriage. It was in Genesis that God said be fruitful and multiply and promised the coming deliverer after they sinned. Mary would have been disobedient to this command if she did not have a family when it was possible.

God in His sovereignty put Jesus in a family atmosphere growing up in a normal fashion in His culture. How can this be proven? Lets look at all the Scriptures with His mother Mary to see them in their context. In Jn.2:12 we see after the wedding in Cana “ He, his mother, his brothers, and his disciples; and they did not stay there many days. ” This would make sense that they were his immediate family. In a wedding all the family and friends would join together for this joyous occasion. The text makes a distinction between the bloodline and the spiritual line.

John 2:12: “After this He went down to Capernaum, He, His mother, His brothers, and His disciples; and they did not stay there many days.” Notice it makes a distinction between His brothers and disciples (which would be brethren). Brothers is specific as the intent is to show family as it follows his mother. Now we know that Jesus' step dad is already off the scene, why we do not know. So it would only be his mother who would be mentioned in the context of the family.  In Mt. 13:55 and Mk.6:2-3 it says, “is this not the carpenter, the son of Mary and the Brother of James, Joses, Judas, and Simon.” Mt.13:56 adds, “and his sisters, are not they all with us?” Notice the people who question Jesus are using this argument against him as not being anyone special, they know Him and His whole family. If they were not His blood brothers and sisters than Mary was not his mother either! If they are his cousins as Catholics claim then Mary cannot be his mother (but aunt). The whole point Jesus is trying to get across is that those who have a spiritual common ground are ones real family, the family is not just where you are born into. A perfect example of this is when Jesus on the cross turned to his mother and said of John ( Jn.19:26) Woman behold your son, then to John  “behold your mother.” Neither was related by blood and this is why the Greek word adelphous (the word for a blood relationship) is not used. 

Why did Jesus gave his mother to John? Because of what Jesus said previously when his mother and his brothers and sisters showed up outside as He was teaching, “Who is My mother and who are My brothers?” And He stretched out His hand toward His disciples and said, "Here are My mother and My brothers! “For whoever does the will of My Father in heaven is My brother and sister and mother” (Matt 12:48-50). His own family (except Mary) did not believe who he was so they could not do God’s will. So he could only entrust his own mother into a believers hands. John was close to Jesus and He could entrust him with his mothers keeping.

 Luke 8:19-21 also records His mother and brothers coming to see Him but cannot get near because of the crowd. He's told that they are outside wanting to see him, and His response is “my mother and brothers are those who hear God's word and put it into practice.” In Mt. 12:46 is a different account, the same situation happens, and He gives a similar answer “Who is my mother and who are my brothers ... here are my mother and brothers! Whoever does the will of my Father in heaven is my brother sister and mother.” Notice each time it is put in a family setting of mother and children  traveling with each other. Some say these are the children of the other Mary. What would they be doing with Mary, Jesus’ mother each time she is mentioned? Why would they be called a family if they are not?

For one to discount the setting of these records as being Mary’s children, they would also have to refuse that Mary was a mother even to Jesus. In other words if He didn’t have brothers than by the same measure He didn’t have a mother. Jesus seemed to recognize the spiritual bond of those who followed His teaching taking precedence before the physical relationship in the family. We find that not only did His neighbors and countrymen disbelieve His claims as Messiah but His own family. Psalm 69 is a Messianic Psalm which Jesus quoted and applied portions to Himself a number of times.  Within this Psalm we find something very revealing. Psalm 69: 4-9 “Those who hate me without a cause are more than the hairs of my head; Those who would destroy me are powerful, being wrongfully my enemies, What I did not steal, I then have to restore. … Because for Thy sake I have borne reproach; Dishonor has covered my face.   Because for Your sake I have borne reproach; Shame has covered my face. I have become a stranger to my brothers, And an alien to my mother's children; Because zeal for Your house has eaten me up, And the reproaches of those who reproach You have fallen on me.”  Clearly this shows that Jesus had a family, and they did reject him.  In Jn.7:3: “ his brothers therefore said to Him, depart from here and go into Judea that your followers might see the works you are doing.” In vs.5: “ for even His brothers did not believe him.” This does not have the impact if they are only His cousins, however it does make sense if it is His own family that are in disbelief. Which is exactly the point of the Scripture “even His brothers did not believe him.” These same brothers that are mentioned in Mt.13:55 and Mk.6:2-3 are mentioned by name later in the epistles and Identified as his blood relationship to his mother.  The same ones who did not believe during his ministry became believers after the resurrection. Gal.1:19 mentions James as the Lord's brother. Jude in verse one of his letter calls himself the brother of James. This is the same James and Jude mentioned in the family of Jesus. Coincidence, I think not. The Bible interprets itself on this matter. 

Catholic scholars insist that they were only cousins to preserve their doctrine of Mary being a continual virgin. As we go further we see even more Biblical evidence that counters this doctrine.  Paul writing in 1 Cor. 9:5 says “do we not have a right to take with us a believing wife as do the other apostles, the brothers of the Lord and Peter.”  Here Paul is making a distinction between flesh and blood and a spiritual kinship.  Peter was a brother spiritually but not by the flesh. Peter and Andrew were brothers, so were James and John. But they were not the Lords brothers. They are not used once as His brother  If we are to be consistent we would have to call them cousins since  Mary was to be a virgin all her life. When John the Baptist is mentioned or Elizabeth, they are called relatives. In the Greek this is a totally different word.  The Greek word for brother is adelphos and for sister adelphe.  These mean a shared parentage this comes from its root word delphus, which means womb, showing their source of unison in their humanity.

Examples of this are numerous Matt. 1:2 Abraham begot Isaac, Isaac begot Jacob, and Jacob begot Judah and his brothers.

Matt. 20:24 “And when the ten heard it, they were greatly displeased with the two brothers.” The word is adelphoon. These were blood brothers.

Matt. 19:29 “And everyone who has left houses or brothers or sisters or father or mother or wife or children ...” The word for brothers is adelphous and sisters adelphas. Again the context is the family.

Acts 7:13 “And the second time Joseph was made known to his brothers, and Joseph's family became known to the Pharaoh.

Luke 21:16 “You will be betrayed even by parents and brothers, relatives and friends; and they will put some of you to death.” Notice the distinctions parents and brothers--relatives and friends.

Luke 14:26  “If anyone comes to Me and does not hate his father and mother, wife and children, brothers and sisters, yes, and his own life also, he cannot be My disciple.” Notice this is put in the context of a whole family and the word for brothers and sisters is the same used for Jesus' family.

In Col.4:10 when Paul refers to Mark as the cousin of Barnabas the word used is anepsios. The general word used for cousin is suggenes, which means kinsman and relative, this word is not used for any associated with Jesus and his brothers, and mother.  So we can see when we go back to the original language of the New Testament there is no justification to have their being cousins. Why did He not give his mother into another brothers hands. Does this prove that Jesus had no other family members? Jn.19:26 At the cross Jesus says to his earthly mother. “Behold your son and to John behold your mother.” By Jewish law the oldest son is to entrust his mother to the next of kin. He did not entrust her into the hands of his unbelieving brothers, but to John, His closest believer (the disciple Jesus loved).  He had no other believing family, so He entrusted her into the hands of his beloved disciples care. Jesus knew John would outlive all the disciples and brothers in the family, so she was assured a total care for as long as she lived.  Jesus viewed His spiritual family as more binding than just blood. We’ve heard blood is thicker than water in the family, Jesus thought the Spirit was thicker than blood.

In Acts 1:14 after the resurrection when the apostles are mentioned continuing in prayer the women are there, Mary is specifically mentioned as “the mother of Jesus, and with his brothers” in the upper room.  The word is again adelphos-meaning a brother, born of the same two parents or only of the same father or mother. The context bears out the point  that Jesus' mother and family were present. We know that Jesus' brothers who did not believe became believers right after the resurrection and here they are alongside the other beleivers(Gal.1:19; Jude 1). What Mary once kept hidden in her heart was no longer necessary.  The book of Luke and his details of the virgin conception were probably generally known to the Church at this time and he could have possibly talked to Mary or someone trustworthy who talked with Mary personally about this.

In the Encyclopedia of Catholicism in which 150 Catholic scholars participated in, on pg. 198-199   “the linguistic evidence for brothers meaning cousins is very thin, we have but one example where a cousin might be called a brother 1 Chron. 23:22  moreover Hegesippus calls a certain Symeon the second bishop of Jerusalem another cousin of the Lord ( Eusebius Ecclesiastical history 4,22,4 distinguishing him from James the just brother of the Lord)

No linguistic evidence warrants our interpreting gospel passages about Jesus brothers and sisters as his cousins.  Cousins of Jesus when noted were called just that, cousins not brothers. Therefore New Testament authors apparently understood Jesus brothers as blood brothers not as cousins or stepbrothers. To sum up what the Bible teaches on this subject- Jesus was miraculously conceived by the Holy Spirit before Joseph married Mary. Both Mary and Joseph proceeded to have a large family, He was born into a average size family in the first century.