Mystery of Mercy

I am the woman at the well, I am the harlot
I am the scattered seed that fell along the path
I am the son that ran away
And I am the bitter son that stayed

My God, my God, why hast Thou accepted me
When all my love was vinegar to a thirsty King
My God, my God why hast thou accepted me
It's a mystery of mercy and the song, the song I sing

I am the angry man who came to stone the lover
I am the woman there ashamed before the crowd
I am the leper that gave thanks
But I am the nine that never came

My God, my God, why hast Thou accepted me
When all my love was vinegar to a thirsty King
My God, my God why hast thou accepted me
It's a mystery of mercy and the song, the song I sing

...

© 2002 New Spring Publishing, Inc. / By Andrew Peterson and Randall Goodgame.

I think this is a brilliant song*. It captures the perversity of sin that we are so capable of being both 'sinner' and 'pharisee' - profoundly impure yet judging others, utterly condemned yet condemning others, needing God's grace more than anything and showing no grace to others. How like that I can be even now I know God's grace. It describes how this depravity affected even our professed or felt love for God: all my love was vinegar to a thirsty King. And so it point us to the cross, calling us to wonder at the mercy of God. The Mystery of the Mercy. But not now an obscured mystery: at the cross the mystery of mercy is revealed. It is only because Christ cried, "My God, my God, why hast thou forsaken me?" that we can wonder, "My God, my God, why hast thou accepted me?". It's a mystery of mercy and the song I sing.

[*NB full lyrics can be found here. I don't understand how I can be 'the seed that fell along the path' when Jesus said that the seed was the word of God. I'm sure there's some poetic-theological thing I'm not getting though.]