Why is Mary Important?

Mary's part in the Incarnation

With the whole Church I acknowledge that Mary, being a mere creature fashioned by the hands of God is, compared to his infinite majesty, less than an atom, or rather is simply nothing, since he alone can say, "I am he who is". Consequently, this great Lord, who is ever independent and self-sufficient, never had and does not now have any absolute need of the Blessed Virgin for the accomplishment of his will and the manifestation of his glory. To do all things he has only to will them.

However, I declare that, considering things as they are, because God has decided to begin and accomplish his greatest works through the Blessed Virgin ever since he created her, we can safely believe that he will not change his plan in the time to come, for he is God and therefore does not change in his thoughts or his way of acting.

God the Father gave his only Son to the world only through Mary. Whatever desires the patriarchs may have cherished, whatever entreaties the prophets and saints of the Old Law may have had for 4,000 years to obtain that treasure, it was Mary alone who merited it and found grace before God by the power of her prayers and the perfection of her virtues. "The world being unworthy," said Saint Augustine, "to receive the Son of God directly from the hands of the Father, he gave his Son to Mary for the world to receive him from her."

The Son of God became man for our salvation but only in Mary and through Mary.

by St. Louis de Montfort