This is a very unfortunate topic for me to have stumbled on to… because I could go on for hours and hours!

I have always thought that (apart from the intensity and majesty of the Word of God) music is the first medium by which God speaks to us; or, at least, to me! Sacred music specifically has a very special purpose! It literally consists of our fellow human beings, our brothers and sisters, piercing our hearts with divine glory. Chant, Polyphony, Baroque, and most Classical sacred music has this tremendous effect.
For me, there are three distinct levels of the imagination which are spoken to by sacred music.
The Gregorian-notation chants activate the highest, most perfect and utterly simple realms of the human mind. This music speaks to the kernel of our souls! It is the ‘music of God’, which exposes His holy Word without any accompaniment or embellishment. Every note covers a word or syllable, and God’s sacred simplicity is reflected in its directness. You might call simple monophonic chant “blunt”. This is the world of the Divine Trinity, ever in simple communication and communion with each other as One God! There is no polyphony: only the ever-rotating melody of a single Lord echoed in love upon Himself.
The Polyphonic chants activate a slightly lower realm, which ironically seems much higher to us because of its complexity.

I believe polyphonic music is an echo of the angelic salutations to God; for example, I firmly believe the Seraphim sing in polyphonic parts when eternally praising Him! Whenever I hear a Mass, Requiem, Psalm, or Motet by Lassus, Palestrina, Byrd, or Tallis, I know the Kingdom has opened before my eyes. All the terraces, meadows, fields, avenues, forests, oceans, distant stars, and emerald blades of grass consummated in the Heavenly Jerusalem are here represented. It’s a climax of anywhere from 3 voices to 40 voices, after all. It’s a world without simplicity, where everything shines so brightly and with such luminosity that it must dazzle the soul.
The Baroque settings reach the climax of human passion and glorification of God, but are on the lowest level of the imaginative impulse.

I say they are lowest because the Baroque era introduced musical instruments into the fray. This is not necessarily bad or good, but it does bring the purely spiritual wonderment of angelic voices down to a more earthly level. Often, this is the first type of music which leads us to higher, less “base” sacred music. Baroque settings are distinct, in the imagination, from the otherworldly simplicity of Chant and the supernatural complexity of Polyphony, because the Baroque’s man-made orchestras and organs are ‘secular’. The Holy Mass on Earth, accompanied by pomp, circumstance, authority, and shining lights, is what I see in the Baroque!
In my sprawling inner-world, Gregorian Chant is equal to God’s conversation within the Trinity. Polyphonic music is equal to the endless billions upon billions of angels ever-communicating with God. Baroque (and Classical) music is equal to a royal ceremony in honour of God the King, put on by His poor little children, the human race. I suppose I could go further and say that Romantic-era hymns, with their simple emotion and piety, are like the private prayers of children… you know what I mean.
Each genre in sacred music has its own symbolic representation of a position in the hierarchy of the Universe. How can anyone hear the single voice of Gregorian music echoing down the corridors of an ancient church and
not think of God’s voice resounding in the Halls of Might at the end of time? How can anyone hear the polyphony of all the Renaissance years and
not take away a sense that the glorious army of martyrs, prophets, apostles, angels, and saints marches to the horizon to fight the good fight, and to win the race with Satan? How can anyone hear the circumstance of modern orchestral accompaniment of the ancient chants, and
not pick up something of the eternal majesty of God our King, presiding over a massive congregation, all bowed before Him?
Music is the greatest gift in the Universe, after life and Christ.