This might be true of architecture, but I do not think it true of music.
There are some concertos by Bach, for example, which beautifully express the agony of man's inability to know God. Five centuries later we can listen to it, and many people will be hard-pressed to say they aren't made a little sadder by it. When you say "this piece was designed to express the impossibility of understanding the divine", many people, including secularists, nod their head in agreement.
This isn't to say that religion is correct, only that the trappings of religion touch a nerve that is touched by art - and that music that was deliberately designed to touch this same "chord" (ok, sorry, sorry) still does so today...