Got this from the good folks over at *culture is not optional:
"What is Christian in art does not lie in the theme, but in the spirit of it, in its wisdom and the understanding of reality it reflects. Just as being a Christian does not mean going round singing hallelujah all day, but showing the renewal of one's life by Christ through true creativity, so a Christian painting is not one in which all the figures have haloes and (if we put our ears to the canvas) can be heard singing hallelujahs."
H.R. Rookmaker, Modern Art and the Death of a Culture