Music’s appeal is in its power to evoke emotions. The possibilities span the whole range of human emotions, but possibly the most powerful is the sensus pulchritudinæ, the sense of beauty. The sense of beauty, in its turn, is so forceful and persistent because it can be stimulated in two different ways: the logos and the pathos, corresponding roughly to the intellect and the emotions, respectively.
The pathos is immediately and viscerally recognizable. The logos takes study. Ideally, the pathos should point the logos in a fruitful direction, and the logos in turn should sensitize the pathos to things it couldn’t see before. It is as inhuman to dwell forever in pathos as to abandon it for logos.
Art – and music in particular – is a medium of the pathos. A primarily logos-based appeal won’t translate well. For example, the sort of beauty I find in economics (of which I’m a student) is better expressed in treatise than in song. An album about macroeconomic fluctuations would have a difficult time hitting the sensus pulchritudinæ. Similarly, as beautiful as the study of physics reveals the universe to be, a song about the wave-particle duality would be more an entertaining novelty than a true appeal to the sense of beauty.
(Incidentally, there are very good rap videos on both subjects. One might gather from this that the easiest way to translate logos directly into pathos is by wrapping it in a layer of irony, a pathos quite far removed from the sense of beauty.)
On the other hand, there are a number of themes which can appeal directly to the sense’s pathos. I’ve been greatly inspired by innumerable musicians who are inspired by nature. Nature is something which can be immediately and viscerally appreciated. But once it hits logos, you’ve moved into biology. I don’t know of any nature-inspired bands made up of biologists (Botanist, maybe?). Cultural heritage and nationalistic pride is another appeal to pathos which inspires a lot of musicians. But once that hits logos, you’ve moved into political science or anthropology. In both cases the logos is something different from the pathos that inspired it.
Christianity, on the other hand, is present as fully in its logos as in its pathos. C.S. Lewis once remarked in a letter to Sheldon Van Auken that “It is only Christianity which compels a high-brow like me to partake in a ritual blood feast, and also compels a central African convert to attempt an enlightened universal code of ethics.” This is the unique power of the sacred, that its hymns and its theology stand side by side on Sunday. On what other subject can the man of system commune with the man of song?
To focus the intellect on the subdued melancholy of nature is to smother it. Like most pleasant feelings, it is a fragile thing which must be enjoyed in the moment. Nationalism, certainly, collapses under sustained reflection. Economics and the natural sciences on the other hand, as beautiful as they are, cannot be appreciated without sustained reflection, making them inaccessible for most people. It is only Christianity which can stir both the bowels and the brain. It is the only pathos which doesn’t reach a dead end at the intellect.
Religious-themed music has, unfortunately, largely given up on communicating the sense of beauty, in favor of other pathoses ranging from gratitude to fun. There is, of course, nothing wrong with these, nor with the music that appeals to them. But it is the sense of beauty in particular which characterizes the profoundest art, and it is this sense to which Christianity, more than any other potential theme, is uniquely well suited to appeal.