Regarding the Immaculate Conception, Jesus took 100% of his humanity from his mother. It would seem only fitting that Mary would be sinless to pass on her genetic code to her son.
In addition, I believe we are in agreement that Mary is the second Eve (as forementioned in Genesis) and Eve was created sinless. It is logical that Mary was also created sinless.
To me, Immaculate Conception is not a difficult concept considering that God chose Mary to carry His humanity, Jesus Christ, who was fully God AND fully Man. And Mary, of her free will, said YES to God (which, He of course knew she was going to do).
God bless!
But Mary had free choice right ..what if she had said NO??
More to the point...Why did Jesus need a sinless mother to carry His humanity?
He chose to be born in a filthy stable. If it was necessary to escape sinful man he could have just assumed a human body and come on the scene as a man..But He chose to be subject to all the experiences and temptations of man...He walked filthy roads and had fellowship with sinful men
Mary said she needed a savior..she knew the scriptures why would she say she was sinless
BTW this is an insignificant doctrine to me..only significant because a cult of Mary worship has grown around it...She is being made a god..