One thing that a lover of music must be absolutely aware of is the fact that much music theory after 1914-1920 is fundamentally designed to undermine hope and faith. Arnold Schönberg, Anton Webern, Alban Berg, Iannis Xenakis, Krzysztof Penderecki, and Elliott Carter are all famous examples of this.
Penderecki, for example, is a Roman Catholic, and yet there is a cynical terror in his music, filled with an absolutely hope-less impulse of pure darkness. His "Threnody for the Victims of Hiroshima" of 1960 greatly influenced modern Ambient Music, because it's basically an endless stream of soul-breaking noise. It sounds as if the violins are being tortured to death; which, on reflection, seems to be fitting for the subject, but it still ends in death and cynicism. Similar to this is the work of Schönberg, whose atonal music of the 1920's is basically a faster version of modern ambient music; or, rather, modern ambient music is a slower version of Schönberg's atonality. ;)
In my opinion, we should only listen to music that glorifies God in the Highest places. Atonal music (i.e. ambient) almost universally attacks joy and good feelings. Even those who love atonal ambience and minimalist music (and who win awards for composing it) are always saying how dark it is, and how much it reminds them of the depression of modern existence. In their music rests the shadows of an empty, purposeless Cosmos, and in their harmonies is a pessimistic lack of hope in God.
There is beautiful ambient music, to be sure, but both John Paul II and Benedictus XVI gave us very strong reasons for composing art music of the pre-atonal European style. Something about the compositional style of the Common Period, from Vivaldi (1720's) to Bruch (1890's) really transcends all sin and darkness, and imprints hope in us. Surely there are darker moments in classical music, but unlike modern ambient music, the darker moments of classical music always resolve to hope of some sort. Palestrina, Lassus, and Monteverdi may have had a different system of tonality from Purcell and Bach, but they still tried to end on hopeful notes back then.
Today, we have a serious problem with hopeless, joyless music. It serves only as a background to our daily activities, and not a very good background at that. We need the soul-stirring joy of full string orchestras proclaiming God's glorious, eternal happiness through His sons Mozart and Dvořák.
Do not be afraid*