It's difficult to accept for a lot of people because they think that somehow the Virgin Mary herself had something to do with her sinlessness - that it was through her virtue or her own conduct that she did not sin. And that of course would be preposterous and even monstrous in one of God's creatures.
That is not the case -- it was entirely through God's miraculous grace and glory that the Virgin was preserved from sin, not by any means through her own merit.
If you think about it, it does make sense. God works so many miracles, major and minor, that he would certainly preserve His own mother from sin. As the new Ark of the Covenant, bearing God within her own body and - perhaps more importantly - having the nurture and raising of Him until He began His public ministry, the Virgin Mary would have to have the strongest divine support to shoulder that awesome responsibility.
Thanks very. Although first a Christian, and second a Baptist, I view unity in the overall Body of Christian believers to be something we need to dearly hold to in These Days. Your explaination is workable across the Faith, and helps me.