Lyric discussion by verytired 

Cover art for Remain Nameless lyrics by Florence + the Machine

This sounds to me like a description of a fallen angel/demon. It was "born in a big grey cloud, screaming out a love song..." brought into existence to worship God, taking part in the music that is described as taking place continually in heaven. Now, cast out of heaven, it masquerades as a spirit guide, or... call it what you want. It's there when you need it, if summoning is your thing. It certainly fits with the themes of other songs on Ceremonials.

My Interpretation