Doesn't grace mean "unearned favor"? If Mary was full of grace ("unearned favor" or "a favor or blessings bestowed as a gift") does that mean she was sinless? It doesn't seem like a logical conclusion to me.
Sanctifying grace refers to that in Christians by which they are transformed into the adopted children of God. The share in divine life which God offers created persons is a real regeneration, a second birth. Christians possess a new life which is their own (see Rom 6:4); they are new creatures (see 2 Cor 5:17), new men and men re-created in justice, holiness, and truth (see Eph 4:24). This new life is "grace" because it is a divine gift, "sanctifying" because it really transforms a person with the holiness of divine life. . . .
The expression actual grace is used in various contexts with diverse references. The common element lies in the fact that the various realities referred to move people to act in ways which positively contribute to God's redemptive work. Thus, actual grace can refer to God's causality, insofar as God brings sinners to conversion and causes the good deeds of the saints. It can refer specifically to the work of the Holy Spirit in Christians, helping them in their weakness and nourishing their holiness.
Sometimes "grace," in the sense of "actual grace," refers to created entities conducive to anyone's salvation or the good of the Church. A pious thought, a chance encounter, or even a difficulty which conduces to holiness is called a "grace." (Christian Moral Principles [Chicago: Franciscan Herald Press 1983], 1:614)
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