Church music with artistic pretensions is not opposed to the essence of Christian liturgy, but is rather a necessary way of expressing belief in the world-filling glory of Jesus Christ. The Church's liturgy has a compelling mandate to reveal in resonant sound the glorification of God which lies hidden in the cosmos. This, then, is the liturgy's essence : to transpose the cosmos, to spiritualise it into the gesture of praise through song and thus to redeem it; to 'humanise' the world.... the liturgy demands an artistic transposition out of the spirit of the faith, an artistic transposition into human music which glorifies the Word made flesh. Such music must obey a stricter law than the commonplace music of everyday life : such music is beholden to the Word and must lead to the Spirit.
Hence church music must find its way whilst constantly contending in two directions : in the face of puritanical pride she must justify the necessary incarnation of the spirit in music, and vis-a-vis the commonplace she must seek to point the spirit and the cosmos in the direction of the Divine. When the effort is successful, it is of course a gift; but the gift is not bestowed without the preparation which we offer through our own effort. When this takes place, then it is not a matter of exercising a mere hobby without obligation, but rather of living out a necessary dimension of Christian faith and in so doing, retaining a necessary dimension of what it means to be a human being. Without both of these dimensions, culture and humanity irresistibly decay from within.
Joseph Cardinal Ratzinger (1977) (source: http://www.ordoantiquus.org/musica.html)