You probably have got a typo there - I think the gospel is called "The Forgiving Father" (or possibly The Loving Father) - I don`t recall God described as being prodigal in the bible ;-)This caused me to pause. Had I erred in the post? Or is this an instance of confronting the limitations of human language about God?
Herbert McCabe draws a distinction between static words and growing words. Static words are basically words like "jam jar" and "stapler" and "chair" - nouns whose meaning remains stable over time. My nephew Quinn can learn (probably by getting his hand stuck in it) the meaning of the word "jam jar" and in twenty years, the meaning of "jam jar" will probably be relatively the same. This is quite probably a good thing: we live out our lives surrounding by common objects, objects with rather stable names attached to them.
Yet there is another category of words he calls "growing words." These are words whose meaning changes over time. For a child of six, the word 'love' means something like 'is nice to me.' For a woman married fifty years, the word has a different meaning, a meaning that has grown over time. 'Forgiveness' for a teenager may mean "I am no longer grounded." For an adult, the same word has grown to mean "Healing of a relationship threatened by my thoughtlessness or callousness."
A 'growing word' indicates that there is a category of language that isn't quite pinned down and neat. Some of our words - love, beauty, grace, forgiveness, friendship, sorrow, etc. - change over the years, gaining new and deeper meanings, subtlety and nuance, with time and maturity.
It is true that the Gospel does not label God as prodigal. The word itself bears the meaning of 'spending extravagantly.' Can we not, however, see the prodigality of God in our experiences of grace? Those times when I have wandered far and feel the deep longing for communion, am I not embraced prodigally by the Father's embrace? When I see the bountiful harvest in places where women and men strive courageously to live out the Gospel, am I not a witness to the prodigality of grace? Calling God prodigal does not indicate that he wastes his love...it means only that he doles out grace recklessly and lovingly.
When we speak of God, we must have a care to realize that our language is always frayed about the edges. Our words, even when applied literally to God, are limited. I know the meaning of 'good' or 'true' and I speak well of God when I use these words. Yet my notion of 'good' and 'true' is still growing, still evolving, and although I speak rightly of God, I do not speak exhaustively. The mystery of God is not evacuated through any of my words. Hence it is that in prayer and contemplation, I find myself falling silent when confronted with this Mystery. Rather than filling the void with my words, I surrender to the quiet stillness and know the One who defies being captured by language and into whose depths I desire to plunge myself ever more deeply.