So did God choose Mary because He knew she would be the only human ever to exist to choose not to sin, or did God create Mary special so that she wouldn't sin? First, Mary is not the only human ever to exist to choose not to sin. Jesus also is a human who chose never to sin. And millions of babies have died that never chose to sin.
Second, we shouldn't think that Mary's perfect obedience is something that Eve could not have done, as if Mary was either unable to sin or less able to sin than was Eve. The only sense in which God "created Mary special" was, as Mrs. Don-o explained, creating her without original sin, like Eve before the Fall. But creating Mary without original sin did not necessitate that Mary never sin. In other words, creating Mary without original sin did not take away Mary's freedom. Mary, unlike Eve, chose to obey God. Yes, God 'foresaw' Mary's obedience, and chose Mary to be the mother of His Son knowing that she would freely choose to obey. But yet Mary too rightly could have said, "What do I have that I did not receive?" So the two truths must be held together and not seen as detracting from the other: Mary was free, and all of Mary's goodness came from God.
-A8
I just think it's weird the God choose someone who wouldn't sin to be Jesus' mother while he chose someone who would sin to be in the garden of eden.
It's sounds like a nature versus nurture thing. Adam, Eve, and Mary all had perfect natures. Adam and Eve were nurtured by God and chose sin. Mary was nurtured by sinful parents and chose not to sin. Weird again.
It also sounds like your saying it was easier for Mary not to sin because she had a purer nature than normal humans.
I just can't get over all of this unnecessary weirdness. A virgin birth from the house of David is amazing to me. All of this esoteric additional mysticism is kind of interesting, but calling the wrath of God, Peter and Paul down upon anyone who denies it seems pretty harsh.
And the final weirdness is that none of the Marian theology appears in any of the 3 main creeds. According to the creeds, Mary was a virgin when she gave birth. That's it.