(Luke 8:19-21) Many Catholics argue that when the Bilbe referes to brothers of Jesus, that these are spiritual brothers and not blood relatives.
Luke 8:19-21 makes a clear distinction between spiritual and blood brothers and proves that Mary did in fact have other children.
THE CATHOLICS say that in the scripture when it says brothers it does not mean brothers but cousin.In both of these verses, if the brothers of Jesus are not brothers, but His cousins, then who is His mother and who is the carpenter’s father? In other words, ‘mother’ here refers to Mary. The carpenter in Matt. 13:55, refers to Joseph. These are literal. Yet, the Catholic theologian will then stop there and say, "Though ‘carpenter’s son’ refers to Joseph, and ‘mother’ refers to Mary, ‘brothers’ does not mean brothers, but "cousins." This does not seem to be a legitimate assertion. You cannot simply switch contextual meanings in the middle of a sentence unless it is obviously required. The context is clear. This verse is speaking of Joseph, Mary, and Jesus’ brothers. The whole context is of familial relationship: father, mother, and brothers.
The bible even names them.
Matthew 13:53-56 says: "When Jesus had finished these parables, he moved on from there. Coming to his home town, he began teaching the people in their synagogue, and they were amazed. ‘Where did this man get this wisdom and these miraculous powers?’ they asked. ‘Isn’t this the carpenter’s son? Isn’t his mother’s name Mary, and aren’t his brothers James, Joseph, Simon and Judas? Aren’t all his sisters with us? Where then did this man get all these things?’"
Other Scripture verses which specifically refer to Jesus’ brothers are: