Q. Did God know that Mary would say “yes” to bearing His son? If so, then didn’t He preserve her from sin so that He could basically “use” her to fulfill His plan?
A. God respects the free will of every human being. We can choose to either embrace the graces and vocation that He has created for us as our path to sanctity and discipleship, or to forsake them and follow our own way. So, too, it was with Mary. Pope Pius IX declared in the dogma of the Immaculate Conception that Mary “was from the first moment of her conception, by a singular grace and privilege of almighty God and by the virtue of the merits of Jesus Christ, Savior of the human race, preserved immune from all stain of original sin” as well as from all personal sin throughout her entire life (CCC 491). This means that God gave Mary all the graces and blessings that she would need in order to make her YES to Him. However, God did not force her to do so. He allowed her, in total freedom, to say yes to His plan. As a humble handmaiden, she corresponded to this special grace and said, “Let it be done unto me according to thy word!” God did not simply give her this grace to use her but to equip her for her vocation as Mother of God. He made her a pure vessel for His son as one Full of Grace.
This shows us yet again that the Immaculate Conception of Mary – her preservation from all sin – is not meant to glorify Mary, but to show how this blessing comes totally from the glory of our Lord Jesus. It is only because He would later die on the Cross that Mary could be saved and preserved from all sin. Mary required salvation just as each of us do; the difference is that God “pre-saved” her because the sacrifice of love which is the Cross is not something confined to a particular moment in history. The effects of this redemption reach out into the past, present and future. Thus, Mary is saved and made immaculate in anticipation of what we all received through the sacrifice of Jesus and the gift of baptism. Think of it as one person being saved from a disease by a vaccination in order to prevent it, while another is saved from the same disease by an operation to cure it – both are saved yet the order of events is different (Peter Kreeft, Catholic Christianity, 410).