[Antoninus]

Yes, she was human, which indicates that she was indeed a sinner, as are/were all humans, with the exception of Jesus Christ.

Personally, I'll take St. Augustine's opinion over yours:

In refuting Pelagius, St. Augustine declares that all the just have truly known of sin 'except the Holy Virgin Mary, of whom, for the honour of the Lord, I will have no question whatever where sin is concerned" (De naturâ et gratiâ 36).

Heck, even another Augustinian, Martin Luther--the inventor of sola scriptura, himself--was closer to the truth on this matter than you are.

[alnick]

Personally, I'll take St. Augustine's opinion over yours:

Not mine, but the Bible. Romans 3:23.

We'll just have to disagree. :-)