The overriding impression here is emptiness. It is a congregation of nobody.
Apart from that unmistakeable comment on the current state of (roman) (catholic) (christian) religion, the image has visual appeal too: the contrast between the lower and the top half could hardly be greater: a jumbled mess (but well ordened) of straight and narrow lines below, and the elegance of gothic curves and arches above it.
It is like you are saying that we mortals, locked in our narrow and claustrophobic maze of squareness, are aspiring (or should be aspiring) to something more elevated.