This episode is reported in two of the Gospels (Mark and Luke), which points to its relevance.
While the Lord spoke to the people who accompanied Him, His mother and brothers came to talk to Him, but could not get close because of the crowd (Luke 8:19) which did not open a way for them, even knowing their kinship. What He said on this occasion, when told that his mother and his brothers were there seems to be in contempt of His family, but there is really a deeper meaning to it.
The people of Israel is a special people, created by God in order to glorify His name on earth, in the midst of a rebellious and idolatrous humanity. God granted them the name Israel starting from their patriarch Jacob and his descendants, meaning "Prince who struggles with God".
Mary the mother of Jesus was an Israelite, a descendant of the Royal House of David, promised in marriage to Joseph, who not only was of the royal household, but also of the royal line: he would have been entitled to the throne if this had not been undone with captivity, centuries earlier. This was then the woman chosen by God, through whom the Son of God came down from his glory in heaven to the depths of this world, taking the form of man among His people: she was His creature, because she was created by Him as well as all things (Colossians 1:16).
Being born from her, He ensured that His ancestry was well known, through the Royal House of Israel, the people that God prepared for Himself, and, through Abraham, went back to the first man, Adam (Matthew 1:1-16 and Luke 3:23 to 37). No other people on earth keep the record of their ancestors so meticulously up to Adam as the Israelites.
Mary and her other children, half-brothers and sisters of the Lord Jesus, together with the rest of the people of Israel, were those with whom He had chosen to have affinity in the flesh, for His divine purposes. They were His relatives, His compatriots on the human side, of the same “blood” as He, with the same ancestors. It was certainly a great privilege, as much for Mary, as for all Israelites. Neither Mary nor the rest of the people were privileged because of merit: it was entirely by the grace of God, as the angel Gabriel declared and Mary humbly acknowledged. (Luke 1:30, 48-49, 54-55).
The tradition of the catholic churches has sought to give relevance to the family ties of Mary with the Lord Jesus in their spiritual relationship, in disagreement with the clear frontal statement made by the Lord Jesus found here: "whoever does the will of My Father in heaven is My brother and sister and mother. “
This tradition also gave rise to the myth that Mary remained a virgin until she died. This text belies such an invention, along with several other texts (Psalm 69:8, Matthew 13:55, Mark 3:31,32, 6:3, John 7:3,5, Acts 1:14, 1 Corinthians 9:5, Galatians 1:19). Her marriage with Joseph was consummated after the birth of Jesus, and they had several sons and daughters.
The relationship of the Lord Jesus with His mother and brothers was purely human, "according to the flesh", as part of His family, the people of Israel, and of humanity. Being the eldest son of Joseph and Mary made Him a legal heir to the throne of David, and gave Him the right to be King of Israel (as Pilate wrote on the cross, to the chagrin of the Jewish religious leaders).
When declaring that whoever does the will of God is His family, He was not renouncing His family according to the flesh. As eldest son, He continued to look after the welfare of His mother. This was proven when, as He gave His life on the cross, He passed that responsibility to the "disciple whom He loved"- the apostle and writer John (John 19:26-27). However, the Lord Jesus never ceased to be the Son of God, the Father of eternity! Any human kinship He underwent during His brief stay in this world was just circumstantial.
The Pharisees and religious leaders of the people rejected His identity as the Messiah of the prophecies. They now sought to undermine His good name, claiming that He cast out demons by Beelzebub, and waited for an opportunity to kill him. Even His mother and her children had not yet perceived the transcendental quality of the person of the Lord Jesus, and did not see beyond His human side, stuck with family ties and compatriots.
Mark informs us that, on this occasion, "when His own people heard about this, they went out to lay hold of Him, for they said, "He is out of His mind" and so joining in with the scribes and Pharisees. (Mark 3:21). His own brothers did not believe in Him (John 7:5).
Up to this point, the Lord Jesus had limited his ministry to the "lost sheep of Israel" to whom He had sent His disciples to preach exclusively (chapter 10: 6) because “My people have been lost sheep. Their shepherds have led them astray; they have turned them away on the mountains. They have gone from mountain to hill; they have forgotten their resting place" (Jeremiah 50:6).
Now the Lord Jesus clearly defines that the kinship of human order, whether the mother, brothers or sisters that he had, did not have any meaning in the Kingdom of God. The closest relationship of the Lord Jesus is with His Father Who is in heaven, God the Father Himself. The only permanent "kinship" He can have is of a spiritual order, and it is with those who hear and do the will of God. These he calls "My mother and My brothers" (Luke 8:21, John 20:17).
Leaving aside the bonds represented by blood kinship according to the flesh with His mother and his brothers, the Lord Jesus will now extend his ministry to all those who receive it, without distinction between Jews and Gentiles. There is no more exclusivity for Israel, due to their disbelief and rejection.
The relationship "after the flesh" is entirely superseded by spiritual affinities. Obedience to God is now the predominant and definitive factor to establish such affinities, without any other distinction.
The same applies to everyone who receives Christ as his or her Lord and Saviour. He said: “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." (Luke 14:26-NKJV). Our spiritual relationship with Christ produces a bond greater than our blood kinship.
Both His mother, and at least two of His brothers (James and Judas) converted and joined His church at Jerusalem according to what we gather from the Scriptures (e.g.. Acts 1:14). However, their blood kinship is not even mentioned by His brothers in the letters that they wrote and which are found in the New Testament, indicating that they gave no value to it. Instead, they claim to be "servants of Jesus Christ" (James 1:1, Jude 1:1).
46 While He was still talking to the multitudes, behold, His mother and brothers stood outside, seeking to speak with Him.
47 Then one said to Him, "Look, Your mother and Your brothers are standing outside, seeking to speak with You."
48 But He answered and said to the one who told Him, "Who is My mother and who are My brothers?"
49 And He stretched out His hand toward His disciples and said, "Here are My mother and My brothers!
50 For whoever does the will of My Father in heaven is My brother and sister and mother."
Gospel of Matthew, chapter 12, verses 46 to 50