Great posts for this column. I also wanted to add a couple of things.
First of all, if you want to make the argument that Mary was a sinner since she offered 2 turtledoves in accordance with Lev. 12 you would also have to make the argument that Jesus must have been a sinner since he was baptized by John the baptist. It was the Baptist who said “I baptize you with water for repentance” (Mt. 3:11); do we therefore conclude that Jesus needed to repent? That is absurd. Jesus was baptized to sanctify the waters of baptism to “fulfill all righteousness” (Mt. 3:15). Mary, being full of Grace and the Handmaid of the Lord is likewise pleased to fulfill all righteousness and to walk in all of the commandments and ordinances of the Lord blameless. Had Mary failed to keep the Law in this regard, these same people would be quick to point out how she transgressed the commandment of the Lord and was therefore a sinner.
Secondly, St. Elizabeth filled with the Holy Spirit exclaimed with a loud cry, “blessed are YOU among women and blessed is the fruit of your womb!” (Luke 1:42) Now if Mary were a sinner, this passage would be erroneous since we know that Eve was created in a state of perfection before she harkened to the voice of the serpent. If Mary sinned one could argue that Eve, at least at one time, was blessed among women being created in a state of perfection. This leads to a deeper point.
Sin puts us at enmity with God. It is inconceivable that God would take His human form from a woman who was in a state of sin and at enmity with him. This would give Satan the opportunity to reproach the Lord Jesus for all eternity. He would be able to say that He (Jesus) was unable to preserve even his own mother from turning against him at one time or another. He would be able to boast forever and ever that before she was His mother, she was his slave and able to say “I had her first”. God would never allow the Devil such a luxury. He would never ever allow his own mother to be numbered among the ranks of his greatest enemy for even the tiniest moment imaginable.
If you were God and you knew from all eternity the woman from whom you would take on human form for the redemption of mankind, wouldn’t you create her immaculate? The 4th commandment says, “Honor thy father and thy mother.” God certainly has the power to preserve a member of the human race from sin (He is God after all). We know that Jesus, being God, kept the commandments of God perfectly. How better for Jesus to honor his own mother than to preserve her from the stain of sin.
If we say that Mary was a sinner, we are saying something very grave and that is that Jesus in essence dishonored his Mother thereby transgressing his own commandment. This cannot be since God would never do anything contrary to his own will.