One of them was arguing that Jesus has blood that was special and did not have sin--as if sin were transmitted in the blood, or that blood in of its self were evil. The fact is when the bible calls blood righteous or blameless it's an expression for the righteousness of the person being killed. It's not refering at all to "sinful blood." To say that blood itself transfers sins is smacking with gnostic doctrine which believes the physical world to be evil. I was continually question by people if "blood passes to the child"-which it generally does not, however DOES occassionally happen, they were trying to argue that somehow this proves Jesus did not get "Mary's tainted blood", yet what they fail to realize if in the womb they themselves do not get their mother's "tainted" blood, NOR THEIR FATHERS! So why are not all men conceived without original sin or "sin nature" as they prefer to say? (As a side note, they seem to be ignorant that a child's blood is determined by a combination of the mother and fathers, eg. if the mother is AA and the father is OO the child will be AO; also, ignorant of the fact that modern biology says the mother is the one that accepts the seed via chemical signals, though neither of these are really relevant to the discussion). Now, continuing she pretends Acts 17:26 somehow proves sin is passed in the blood--though it only says (and only in certain manuscripts) that all men were made of "one blood" (ie Adam), yet she conveniently forgets that Christ too is a "man." So apparently "all does not always mean all" applies here too! Regardless, this verse in no way speaks of sin being passed in the blood. Even Jesus spoke of other people's blood as being "just":
upon you may come all the just blood that hath been shed upon the earth, from the blood of Abel the just, even unto the blood of Zacharias the son of Barachias, whom you killed between the temple and the altar.--Matthew 23:35
Dare we interpret this to mean their physical blood was a better quality than the rest of man's "sinful blood'"? After all, they too were of the "one blood" of Adam! This is the some person I addressed in a previous Question and Answer session over this issue. People continued to argue that Jesus was not of Mary because she was sinful, so He could have "none of her DNA or blood." In this desperation to discount Mary they make Jesus a false Messiah because He had to be of the tribe of Judah to be King. Furthermore, he is called the "seed of David"--so he must be of the "blood line" of David. If He did not have anything from Mary--how was He the "seed" of David at all?
Hath not the scripture said, That Christ cometh of the seed of David, and out of the town of Bethlehem, where David was?--John 7:42
In fact, this is not the only verse in the Scriptures which call Him the "seed of David." St Paul even makes it clear He speaks of Christ being a literal descendant of David by also adding that Christ was of the "seed of David ACCORDING to the FLESH."
Concerning his Son Jesus Christ our Lord, which was made of the seed of David according to the flesh;--Romans 1:3
Another person tried to make an even more desperate against Mary by saying that Jesus' body was prepare in Hebrews means God created a body for Jesus then placed it inside of Mary.
For this reason, when he came into the world, he said: "Sacrifice and offering you did not desire, but a body you prepared for me; holocausts and sin offerings you took no delight in."--Hebrews 10:5-6
Nothing in this verse at all implies God created a body outside of the Virgin Mary, in fact if it did it would contradict the Scripture when it says:
Why does the Archangel Gabriel call it conceiving, if according these Protestants God merely relocated an already made body inside of Mary for Jesus?
Furthermore, why is Jesus refered to as the "fruit of the womb" of Mary if Jesus is not the fruit that was produce from Mary via an umbilical cord? Also, how can these people even argue Jesus is the one being spoken of as the "seed of the woman" in Genesis 3:15 if Jesus is not Mary's seed? (This is an argument from a Protestant prespective, since all Christians are actually the "seed of the woman" spoken of in Genesis, not simply Christ, though He fulfills the role first and foremost and without that seed none of the others ones would prosper in overcoming the serpent).
Why shouldn't we simply believe the Holy Spirit when speaking through Elizabeth the Blessed Virgin Mary is declared to be the "mother of my Lord"?
And whence is this to me, that the mother of my Lord should come to me?--Luke 1:43
In summary: Mary is called the "Mother" of the Lord, Jesus is called the "seed of David according to the flesh" by St Paul, Mary is told she will "conceive" in her womb (not be implanted with a preexistent body), and Jesus is called the "fruit of her womb," so there is NO reason to speculate Jesus was not a physical descendant of the Virgin Mary.
Addition: I have also encountered people objecting to calling Mary the Mother of God on the basis that she did not bear the Father and the Holy Spirit. However, this reasoning is faulty in that it would mean that Jesus is not God since He is not the Father and the Spirit. If such requirements were needed to make Mary the Mother of God, then Jesus, nor any other member of the Trinity maybe called God on Their own since, no person of the Trinity is Himself all Three! Thus the Bible would have errored in Hebrews 1 and Psalms when it has the Father addressesing the Son says "Thy throne of God.."