On the contrary, if Mary received grace, it was because she was a sinner.
Where sin abounds, grace does much more abound.
Where there is no sin, there is no grace because the person is getting what they deserve, not getting what they don't deserve. Grace is only operative when the person doesn't deserve what they are getting.
If Mary was graced, it was because she had sinned.
Sin is not the only condition in which people obtain grace. Jesus is also described as being "full of grace" (John 1:14) and He did not sin. So your rule does not work with Mary OR Jesus. Besides, it is not credible to suggest that God's messenger called her "full of grace" in order to indicate that she was full of sin. Sheesh. "Where there is no sin, there is no grace because the person is getting what they deserve, not getting what they don't deserve. Grace is only operative when the person doesn't deserve what they are getting."
Not so. Grace doesn't ONLY mean something unmerited. A beautiful Messianic Psalm 45:2-3 describes the Messiah (we know this is Jesus) as having had grace poured upon His lips:
You are fairer than the sons of men;
Grace is poured upon Your lips;
Therefore God has blessed You forever.
Gird Your sword upon Your thigh, O Mighty One,
With Your glory and Your majesty.
The Gospel of Luke speaks of the Child Jesus growing in grace:
Luke 2:40
"And the Child grew and became strong in spirit, filled with wisdom; and the grace of God was upon Him."
You can't say the Messiah was graced because He had sinned!
And look at Psalm 84:11
"For the Lord God is a sun and shield;
The Lord will give grace and glory;
No good thing will He withhold
From those who walk uprightly." Likewise Proverbs 3:34-- "Surely He scorns the scornful, But gives grace to the humble."
These make no mention of the "sin" of the recipient of grace, but focus on the fact thew God will not withhold His grace from "those who walk uprightly" and "the humble."
Happily take into account all of these passages, metmom, which will enrich your understanding of "grace."