Consider these words to be merely reflections, not a firmly planted and defended position on my part:
What artists, poets, and musicians can do for us who seek to know God more closely, is bring us into a perspective that we do not get from theology and scholarship. The artist, many times, is bringing us to an angle at which God's transcendence is...not known or understood, but perhaps whispered of. Theology points us to revelation, and the proper way to interpret and apply revelation. Art, for art's origins are mystical, shows us some fraction of the unrevealed, tempering theology by keeping its proclamations and proofs squarely rooted in the context of something bigger than what is knowable.
God Transcendent refuses to be contained or defined. Righteousness, or God-ness, all escape the grasp of the mind. "I Am what I Am" may be the closest we come to bringing it to our experience. God Transcendent will not be told what to do, how to behave, or what true righteousness is. He will show mercy where and when he will show mercy. He will not vote for our candidates, fuel our revolutions, write manifestos for our movements, pass our legislation, or sign our money. He will not be told who He is. Revelation, a descriptor of the vast ocean of God beside the drop of the human soul, is given to disarm the pretensions we have toward owning God.
What does it mean for the artist to be free indeed in her work? Can we put parameters on the content of a piece to insure our lives are not being secretly invaded by sin when we observe, or take part in a piece of music or art? The question is a recurring theme in the New Testament, though more broadly applied to the general practices of everyday life. What can I do?
I might critique art. I might critique a criticism of art. I could have a strongheaded opinion about an artist. I could find one composer to be aesthetically catatonic, or positively vibrant. I could take the inclusive, "there's no such thing as bad art" perspective, or I could say "good art is indicated by the technical mastery of the artist." Or anything in between these two statements. Whatever I'm saying about art, or God in art, or God in culture, I have to be able to admit that all our creations and icons come from somewhere, faithfully representing an inner reality. Whether it's the unpretentious simplicity of a 3-year-old, the peacefulness of a wizened saint, or the dark raving of a haunted personality on the edge of madness. All of these and more represent something common to humanity- they are where we are.
The question, then, do we judge(in the heaviest sense of that word) art by measuring it against some subjective code of righteousness(for there is no other kind, unless you are God), or do we allow the artist's work to reveal whatever it will reveal, committing to God in stark honesty whatever invisible structure is undeniably present and gave it birth?