Actually, the bible does say Mary was without sin. Do remember though that it was through Adam that sin entered the world.
In Luke we're told an angel appeared to Mary and told her she had been chosen by God to bear to life the Messiah.
Mary , in that scripture in Luke 1:28 we are told that Mary was highly favored.
Luke 1:28 [RSV]: "And he came to her and said, 'Hail,
O favored one, the Lord is with you!'"
Strong's Hebrew Greek: charitoo
Thayer's Greek Lexicon:
charitoō
1) to make graceful
1a) charming, lovely, agreeable
2) to peruse with grace, compass with favour
3) to honour with blessings
Part of Speech: verb
Relation: from
Charis G5485 (grace)
1) grace
1a) that which affords joy, pleasure, delight, sweetness, charm, loveliness: grace of speech
2) good will, loving-kindness, favour
2a) of the merciful kindness by which God, exerting his holy influence upon souls, turns them to Christ, keeps, strengthens, increases them in Christian faith, knowledge, affection, and kindles them to the exercise of the Christian virtues
3) what is due to grace
3a) the spiritual condition of one governed by the power of divine grace
3b) the token or proof of grace, benefit
3b1) a gift of grace
3b2) benefit, bounty
4) thanks, (for benefits, services, favours), recompense, reward
Part of Speech: noun feminine
Relation: from
Chairo G5463
Charitoo is a passive participle of
kecharitomenem "highly favored".
Mary was then highly favored or, grace filled, given grace. (See above)
In Christianity Christians are saved by God's grace. God's grace allows for us, indwelt by his Holy Spirit, to live holy and righteous lives without sin because we are no longer in that category of sinner.
Mary was highly favored,
kecharitomenem, grace filled and that is why the angel told Mary she was chosen to bear the Messiah into the world.
She was filled with God's grace, saved, sinless, and therefore was able to bear Christ to life.