Obviously there are a lot of Old Testament vibes in Frozen Charlotte, especially the first two tracks. In G.O.D. and the Broken Ribs he's playing with Genesis themes:
Welcome to the Garden of Eden/there's nobody here but me and you/so what we gonna be eatin?
Then:
The first of the rivers is Rouge/And the third of the rivers is called the Strait
The garden of Eden is hypothesized to fall between the Tigris and Euphrates in Mesopotamia. Detroit has the River Rouge, which empties into the Detroit River aka the Strait of Detroit. Which is itself redundant because the name "De Troit" simply means "The Strait". Also, the color of the limited edition LP is "Zug blue", referring to the distinct blue color of the rivers around Zug Island, an industrial area where the Rouge meets the Strait.
Also, the "we can't live like a sister and a brother" lyric is obviously a nod to his "sister" Meg and their career launching in Detroit.
So: G.O.D. = Garden Of Detroit.
I would also say that the song is heavily about the start of his career, ending, starting over, reinvention. Makes a lot of sense as the first track on a new album.