54And when he was come into his own country, he taught them in their synagogue, insomuch that they were astonished, and said, Whence hath this man this wisdom, and these mighty works?
55Is not this the carpenter's son? is not his mother called Mary? and his brethren, James, and Joses, and Simon, and Judas?
56And his sisters, are they not all with us? Whence then hath this man all these things?
57And they were offended in him. But Jesus said unto them, A prophet is not without honour, save in his own country, and in his own house.
58And he did not many mighty works there because of their unbelief(Matthew 13:54-58).
This is not talking about Jesus and people who followed him when it says His brethren and sisters,but Jesus' family,his brothers and sisters,Mary's children.This is talking of His family.
This is not talking of cousins,but of His family.
Jesus went to His own country and taught them in their synagogue,which they had trouble accepting Him as the savior to come,for they said is not this the son of Joseph and Mary,and his brothers and sisters,are they not all with us,because they were expecting the savior to come having no family,not being born in to this world.
This cannot refer to the brethren and sisters as people that followed Christ,for if it was,they would not have said anything concerning that,and that they said this starting with Joseph and Mary indicates that they were referring to Jesus' physical family,that they are all with them,so they did not believe Jesus was the savior,because they thought He would come not being born in this world,so they thought He would have no family.
25And knew her not till she had brought forth her firstborn son: and he called his name JESUS(Matthew 1:25).
This says that Joseph did not have sex with her,until she had her firstborn son,Jesus,indicating that Joseph had sex with Mary but could not until Jesus was born.
12After this he went down to Capernaum, he, and his mother, and his brethren, and his disciples: and they continued there not many days(John 2:12).
If brethren meant followers of Jesus,it would not have brethren and disciples in this scripture for they would be the same,also it says mother,and then brethren,indicating Jesus' brothers,the sons of Mary.
49And he stretched forth his hand toward his disciples, and said, Behold my mother and my brethren!
50For whosoever shall do the will of my Father which is in heaven, the same is my brother, and sister, and mother(Matthew 12:49-50).
Jesus said whoever does the will of His Father is His brother.Whoever believes in Jesus,He would consider them a brother.
1After these things Jesus walked in Galilee: for he would not walk in Jewry, because the Jews sought to kill him.
2Now the Jew's feast of tabernacles was at hand.
3His brethren therefore said unto him, Depart hence, and go into Judaea, that thy disciples also may see the works that thou doest.
4For there is no man that doeth any thing in secret, and he himself seeketh to be known openly. If thou do these things, shew thyself to the world.
5For neither did his brethren believe in him(John 7:1-5).
Jesus' brethren wanted Jesus to show Himself to the world,for His brethren did not believe in Him.This shows that the brethren here are Jesus' brothers from Mary,for if they were brethren being followers of Jesus they would have believed in Him.