A friend of mine was telling me a story about his niece. She is 3 going on 4, and everywhere she goes she takes this dirty, ragged, old doll with her. Nothing can convince her to love another, more beautiful, more perfect doll. She loves that one. And she doesn't have a reason. She just loves it.
The lesson to this story is that God loves us much like my friend's niece loves her doll. It is not because we are already all nice and beautiful or without fault or defect that, then and only then, He begins to love us. No, on the contrary. He loves us.
In the Gospel of Luke 24:47, before ascending into heaven, Jesus sends His disciples out to preach repentance and the forgiveness of sins. This repentance is not repentance in order to obtain forgiveness, as if one had to buy God's mercy with acts of piety, but repentance in order to open one's self up to receive God's mercy, that is to turn away from sin and toward God, a turning, which, if we go by the story of the Merciful Father and the prodigal son in chapter 15 of Luke, God the Father sees even when we are still "far off," and to which He responds by running out to meet us and embracing us, even leaping over mountains and bounding over hills.
God's love comes first. 1 John 4:10 makes this clear. "In this is love: not that we have loved God, but that he loved us and sent his Son as expiation for our sins."
Fr. Raniero Cantalamessa, the preacher to the papal household, in his book Life In Christ puts it this way (I'm paraphasing). The order of events is not sin, repentance, salvation, but sin salvation, repentence. It is God's overwhelming, relentless and ever-faithful love that leads us to conversion (if we let Him work... we can still say "no").
Mary's example here is important since she said "Fiat mihi secondum verbum tuum" (may it be done unto me according to thy word), and what word has God revealed to us if not the Word, His Son, Jesus (whose name means "Yahweh saves," "I am who saves"). His will for us is this salvation, this communion, His very life. Let us say "yes" to it. Let us say "Amen."