Wow, where to begin - your exegesis is laughable and your hermeneutics are horrible. Caution: It may be quite painful to see your arguments ripped apart with the truth.
Gabriel addresses her, "Rejoice, kecharitomene [past present participle]"
Immediately you demonstrate your lack of understanding of the Greek language. Your PC Greek program may not tell you this, but there is no such thing as a "past present participle." It's either past or it's present, but it can't be both. The correct parsing would have been present active imperative (but I'm sure you knew that, right?).
When the angel Gabriel appeared to Mary and told her that she would conceive a son, she asked, "How can this be since I have no relations with a man?" (Luke 1:34). From the Church’s earliest days, as the Fathers interpreted this Bible passage, Mary’s question was taken to mean that she had made a vow of lifelong virginity, even in marriage. (This was not common, but neither was it unheard of.) If she had not taken such a vow, the question would make no sense.
What a ridiculous statement. Couldn't there have been just a wee little chance that Mary was a virgin when she conceived and bore Jesus and that she enjoyed a beautiful, conjugal relationship with Joseph after that? While I will concede that some of the early church fathers (such as Cyprian) held your interpretation of Mary's statement, you act as if it was the consensus of the church - that is bogus. But even if it was, what difference would it really make. This is your foundational problem: You find one passage that affirms Mary's virginity, and then you look to church history to affirm her "perpetual virginity." What's wrong, couldn't find anything in the Bible to back you up? And of course her statement would have made perfect sense even if she didn't retain her virginity throughout her lifetime. When Christ was conceived, she had known no man - she wouldn't have had to remained a virgin forever for her statement to make sense. The verse says absolutely nothing of her virginity beyond the birth of Christ! It doesn't get much plainer than that!
Mary knew how babies are made (otherwise she wouldn’t have asked the question she did). If she had anticipated having children in the normal way and did not intend to maintain a vow of virginity, she would hardly have to ask "how" she was to have a child, since conceiving a child in the "normal" way would be expected by a newlywed wife. Her response is a complete non sequitur!
Man, are you listening to yourself. You are making absolutely no sense at all. Her statement makes perfect sense when you consider the fact that she was BETROTHED, not married. An Israelite woman could have easily been subject to stoning for having sexual relations outside of marriage. And though betrothal was seen as being very close to marriage in those days, the one thing that it certainly did not include was sex. Based on the fact that Mary was betrothed, and not married, her statement not only makes sense, but to interpret it as I have is to keep the text within it's context, and not some attempt to accomidate errant Catholic dogma. By the way, no one throughout this string ever even cared to mentioned when the perpetual virginity of Mary was officially recognized as Catholic dogma - do you think they're all embarressed, or do they even know?
When Jesus was found in the Temple at age twelve, the context suggests that he was the only son of Mary and Joseph. There is no hint in this episode of any other children in the family (Luke 2:41–51).
And so from what you're saying, we're to assume that Luke 2 teaches the perpetual virginity of Mary - that is nonsense. Have you even taken hermeneutics yet? If you had, then you would no that the argument from silence is the weakest hermeneutic of all. Just because Luke didn't mention Christ's siblings doesn't mean that they weren't there - please don't try and pass over such lame arguments on me. Remember, Luke was writing about Jesus, not his brothers - one would not even expect his brothers to be mentioned - that's just silly.
Jesus grew up in Nazareth, and the people of Nazareth referred to him as "the son of Mary" (Mark 6:3), not as "a son of Mary." The Greek expression implies he is her only son. In fact, others in the Gospels are never referred to as Mary’s sons, not even when they are called Jesus’ "brethren." If they were in fact her sons, this would be strange usage.
Again, your hermeneutics are found lacking much to be desired. While the fact that the definite article is used really proves nothing, I'll concede that maybe it did mean that the people thought there was something different about Jesus. Yet, to argue that it was that He was Mary's only son is ridiculous. Couldn't there be a slight chance that they referred to Jesus with the definite article because He was the only One of Mary's children who claimed to be God and because He went about doing many signs and wonders. If these are the best arguments you have, you're wasting your time. All you're doing is taking a few elementary nuances of the language and attempting to twist them into the dogma of perpetual virginity.
Also, the attitude taken by the "brethren of the Lord" implies they are his elders. In ancient and, particularly, in Eastern societies (remember, Palestine is in Asia), older sons gave advice to younger, but younger never gave advice to older—it was considered disrespectful to do so. But we find Jesus’ "brethren" saying to him that Galilee was no place for him and that he should go to Judea so he could make a name for himself (John 7:3–4).
Please - notwithstanding the customs of the day, how many younger brothers had older brothers who claimed to be the Messiah? Give me a break! Of course they questioned the claims of their brother, even if He was their older brother. I dare say that you would have done the same thing. Your assertions are not grounded in real biblical exegesis!
Consider what happened at the foot of the cross. When he was dying, Jesus entrusted his mother to the apostle John (John 19:26–27). The Gospels mention four of his "brethren": James, Joseph, Simon, and Jude. It is hard to imagine why Jesus would have disregarded family ties and made this provision for his mother if these four were also her sons.
My, my - how conveniently you left out the part about John being the "disciple whom Jesus loved." Would you have wanted your mother entrusted to the care of those who may not have even believed that you were the Messiah? I know that at least James became a believer following Christ's death and resurrection, but you are surely not asserting that all His brothers and sisters were sympathetic with His mission following His death. Aside from all that though, Christ's entrusting His mother to the care of John proves nothing about Mary's perpetual virginity - you are sincerely grasping at straws.
Consider yourself sent back to the Minors - please don't come back up to the Majors until you've got some real exegesis.