Here are some parts of the article which I found important:
"A more clear indication of this occurred when Jesus, as a full grown man, came to his hometown (Nazareth) and began to teach. People from there, who apparently knew his family, stated the following in disbelief:
Coming to his hometown, 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?" (Matt. 13:54-56).
According to that text, Mary had at least four other sons, besides Jesus, and at least two daughters. Some argue that the word "brothers," found in this passage, merely means relatives such as cousins. If that is the true intended meaning, then one must wonder why the Greek word meaning "cousin" (anepsios) was not used there as it was in Col. 4:10:
My fellow prisoner Aristarchus sends you his greetings, as does Mark, the cousin of Barnabas. You have received instructions about him; if he comes to you, welcome him.
Again, in contrast to Col. 4:10, a different Greek word is used in Matt. 13:55 -- adelphos. This Greek word translated "brothers" comes from the word, delphus, which means womb.
Furthermore, we should also focus our attention in upon the word "sisters" in Matt. 13:56. The Greek word for "sisters" is adelphe. It is also found in the following:
Do not rebuke an older man harshly, but exhort him as if he were your father. Treat younger men as brothers, older women as mothers, and younger women as sisters, with absolute purity (1 Tim 5:1,2).
As in Matt. 13:56, the usage of adelphe in 1 Tim. 5:2 means natural sister born as to the same mother. The context from verse 1 shows the meaning to be the natural family. This is how the same Greek word must be understood in Matt. 13:56, since spiritual sister can't fit the context. The virginity of Mary was temporary."
I also found parts of the following significant:
"So according to Scripture, Mary did not remain a virgin after she gave birth to Jesus. This basic Biblical truth is in direct conflict with what millions of people have been taught, but nonetheless, it is God's word on this subject not any man's. The following is but one errant statement about perpetual virginity of Mary from the Catechism of the Catholic Church:
"Mary ‘remained a virgin in conceiving her Son, a virgin in giving birth to him, a virgin in carrying him, a virgin in nursing him at her breast, always a virgin" (p. 128, bold emphasis mine).
Dear reader, that quote was from the Catholic theologian, Augustine (who also was the original source of modern-day Calvinism). The following is another important quote which shows how Roman Catholicism counters Matt. 13:55:
"Against this doctrine the objection is sometimes raised that the Bible mentions brothers and sisters of Jesus. The Church has always understood these passages as not referring to other children of the Virgin Mary. In fact James and Joseph, ‘brothers of Jesus,' are the sons of another Mary, a disciple of Christ, whom St. Matthew significantly calls "the other Mary." They are close relations of Jesus, according to an Old Testament expression" (Catechism of the Catholic Church, p. 126, bold emphasis mine).
Friend, examine Matt. 13:54-56 for yourself, which shows the subjects as being from Jesus' hometown, thereby enabling them to identify His own mother Mary and His natural brothers and sisters. That passage is clear about this:
Coming to his hometown, 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?"
That passage can't possibly be referring to "the other Mary," as some want us to believe, but Jesus' own mother!
Moreover, trying to sweep all of the New Testament passages away by stating that the phrase "brothers of Jesus" is merely an "Old Testament expression" is to ignore all the other verses which show Joseph and Mary had sexual union, but not until, Jesus was born. Matt. 1:25 couldn't be more clear, especially when considered with Psa. 69:8, which explicitly shows Mary had other children.
Friend, what you will continue to believe about perpetual virginity of Mary is left entirely up to you. You have read what Scripture declares and what the present-day position from Roman Catholicism declares. But know this, you can't believe both declarations, since they are antithetical to each other. One must be in error."