Once you start to say that St Paul obviously didn't mean them then you are making an appeal outside of the text.
Which is something like the correct way forward. Sola Scriptura - the concept that authority comes only from the Bible, is not only not to be found in the Bible, but it is contra-indicated by Christ's own words to Peter.
I will give unto thee the keys of the kingdom of heaven: and whatsoever thou shalt bind on earth shall be bound in heaven: and whatsoever thou shalt loose on earth shall be loosed in heaven.
The Church wrote and ratified the Gospels with the authority given it by Christ. The Church also declared that Christ was both God and Man, it declared and defined the nature of the Trinity, the nature of the sacraments and half an hundred other truths. And one of those truths is that Mary, the Mother of God was indeed conceived without sin.
The theology behind it comes from the nature of the Incarnation. It's a large subject, and not one I can do justice to today: I have to get back to surveying a prison :0(
Suffice to say, Mary's sinlessness comes from her role as Mother of God: she was saved by Jesus just as we all are, but in her case she was saved at conception as a special act of grace as astonishing and as unique as the creation of Eve. Everything about Mary's creation points to Christ's Incarnation - she was made as perfect as she could be, as part of the 'Main Act ' the arrival of God as Man.
Hope this was helpful.
Jesus died for man and the Bible was written for mankind. The Scripture that all have sinned would apply to mankind.
“then you are making an appeal outside of the text”
I don’t see anywhere in the text that says Mary was sinless. If she needed to be sinless so that Jesus could be sinless didn’t her parents need to be sinless for her to be sinless and so on?
I really do not understand.
Well if Mary was made sinless to bear Jesus, making her a special creation, then Anne, her mother, must have been born sinless as well, to bear such a special, sinless creation as Mary!
Ed