A: Mary's sinlessness is the ultimate confirmation of Romans 3:23, and especially of the following verse (24). Mary has been "justified freely by this grace through the redemption in Jesus Christ." Such is the meaning of Luke 1:28 or, more specifically of the expression kecharitomene (full of grace, highly favored one). A pure gift from God, unmerited by Mary, this fullness of grace is the anticipated fruit of Christ's redemptive work.

We regard Mary as the Immaculate Conception, a clear indication that Mary's fullness of grace was God's doing only. What better way to understand sinlessness! Mary is the pure product of God's love for his Son (and those whose paths he would cross): It is not the result of her own works but of grace.

This does not answer all questions concerning grace and works. However, the example of Mary Immaculate is a prime witness of how seriously Catholics take the one mediatorship of Christ in Redemption and the importance of grace over works for justification.