I’m not disputing that Mary wasn’t filled with grace; that is clearly expressed in the Bible. That is not in question.
What I am disputing that being filled with grace implies that one is sinless. We have the example of Stephen being filled with grace, but he was not without sin.
You know, I'm sure that when anyone touched the "old" Ark of the Covenant mentioned in the Old Testament that they died instantly.
That is one reason that Catholics believe that Mary is "The Ark of the New Covenant and that no one, not even her most chast spouse, St. Joseph, touched her in procreating children.
One does not take lightly the Words from the Creed: We believe.....(soon to be "I believe/Credo"....by the power of the Holy Spirit he was born of the Virgin Mary, and became man.
Catholics bow their heads during that phrase of the Creed during Mass because it is so important; bet you didn't know that, huh?