Why would Paul mention a lineage through Mary if it meant absolutely nothing? If Jesus was descended from David through Mary, it would be void. Primarily because lineage was traced through the father. More so, the passage says nothing about Mary, or tracing a lineage through her. It specifically states that Jesus was made of the seed of David according to the flesh. In other ways, he was born according to the flesh, he was conceived according to the flesh.
And Jesus being declared to be the Son of God has nothing to do with his paternal lineage. There is no mention of such. You are reading the Gospels into the works of Paul, and that simply doesn't fly. Especially when we consider that one did not have to have an actual paternal lineage descending from God to be the Son of God. King David was called the Son of God, yet it is accepted he had a natural birth.
Unless one adds to the story of what Paul is saying, there is no reason to assume that Paul was aware of the virgin birth. All you've done here is simply read the Gospels into the works of Paul, which simply is not good scholarship.
  Actually it does, as the verse I used says nothing of what you're saying. It doesn't say Jesus was born of God according to the spirit of holiness or anything about Mary. None of that is in the actual verse. You have added a large amount of information that simply does not appear in the actual verse.
  King David was called the Son of God. I'm not conflating anything here. The fact is others were called the Son of God. You simply can't ignore the fact that the Old Testament labeled others as the Son of God, when not implying that God actually impregnated anyone.
As for other characters, Pagans, who were the son of a god, it simply shows that it was not a special characteristic of Jesus. That various important people were labeled as such.
  You are reading way too much into the stories. Yes, the stories may be widespread, but that means absolutely nothing accept that the story was being widespread. We see a story of Augustus being the son of a god being widespread and being mentioned in various literature. Should we thus assume that he was the son of a god? Or that Caesar was a god? Or even that there were many other gods? Your logic simply does not work here.
As for Mark, there is no reason to assume that Mark thought of Jesus being born of a virgin. Being called Son of God does not mean that one is the actual, physical, son of God. Like I have said before, King David was called the son of God. Yet, no one thought that his actual father was God. The term did not need that. The whole nation of Israel was called the Son of God. The term did not simply mean someone being the actual physical son of God. You need to know the background of the term.
As for John, there is no reason to assume that they thought Jesus was the physical son of God. He never states that. He may say that Jesus was begotten by God, but again, it isn't a very good translation anyway. That is why it has been dropped from the best translations. There is no reason to assume then that the verse actually said that. Again, it just refers to Jesus as being the Son of God, just like King David was.
  Paul doesn't recognize that. He never said that his father was God. He said that God sent forth his Son. That has nothing to do with physically having a child with Mary though. Especially considering that God has sent his son various times before, such as King David.
It simply wasn't important to him, really is all that can be said. He never mentions that she was a virgin either, which shows that it wasn't important, or he simply was not aware of it. The thing that can be said; from Paul, one can not make the assumption that Mary was the mother of Jesus.
He never hammered the point and point over again. He never states that God is the actual father of Jesus. He never mentions that Jesus's mother was a virgin. He never mentions a miraculous birth. Instead, he states that Jesus was born of the flesh, giving the assumption that it is a natural birth.
  Which is exactly why there is little reason to assume that a Jewish writer would make such a ridiculous claim. For Paul, the idea that God impregnated Mary would have been ridiculous, and probably sacrilegious.
  It isn't in the scriptures. The scriptures never mention a virgin birth, until we come to Luke and Matthew. Other than that, the Old Testament never state such a thing, and neither does Paul.