I was just thinking how brilliantly subtle and intensely thematic some of their songs are. Take for example the song "Ouroboros."
The end of this song features a peculiar four chord progression that is quite out of step with the overall presentation of the rest of the song. As with all things in The Mars Volta, this is no accident. This segment of music, I'm all but certain, is intended to parody Evangelical worship songs to criticize the songs and how methodically produced they are, as well as the level of emotional manipulation that is their intent in production.
All but proving that the segment is intended to parody Evangelical music is the line that is sung with it:
"They lost the presence they were holding, looks like the tenants flickered off."
People like to say Mars Volta wrote nonsense or lyrics that don't really mean anything, but lines like this fully evidence that this assertion is the complete opposite of the truth.
The line is built around the trope used in Evangelical subculture of "The presence of God" - meaning that "they" have lost this presence. More specifically, he's punning on the "presence of the lord" due to the presence of the word "tenants." In essence he has embedded the concept "the presence of the Lord" into this segment of music, but contorted it to "the presence of the landlord." Further backing up a directly religious interpretation of this line is the word "flickered off" - one of the main concepts in Evangelical Christianity is the Christian as a "light to the world" - this is frequently referenced as a candle - assuming ones faith can blow out and their light go dark - hence the concept "the tenants flickered off from the presence of the landlord."
Anyway... here's the song, in all it's genius - the last minute is the parody of worship music:
And, here's some worship music if you're unfamiliar with its heavy use of four chord progressions with highly emotive and simple melodies sung along with them - as well as the presence of very "freeform" drumming in the background and the strict reliance on chord strumming rather than melodic instrumentation which is ultimately why that part of the Mars Volta's song stands out, they almost never rely on just chord strumming:
The Mars Volta, of course, isn't remotely the first rock band to criticize Christianity - however, I've never heard it criticized with the level of subtlety and nuance present in their music. Rather than attacking religious people, they seem to see religious people as victims, as is evidenced by the song which follows "Ouroborus" on that album, which starts with an Islamic prayer and seems specifically directed at Islam discussing "bending will (in submission) to deceit:"