No peg because Scripture interprets scripture
There is no scripture indicating Mary was sinless.. Hbr 4:15 For we have not an high priest which cannot be touched with the feeling of our infirmities; but was in all points tempted like as [we are, yet] without sin.
Hbr 9:28 So Christ was once offered to bear the sins of many; and unto them that look for him shall he appear the second time without sin unto salvation.
Then what are we doing here? -:)
Please see pseudo-justins post #322.