Thread:GodzillaIsland7.2/@comment-10363096-20130325234019/@comment-10363096-20130326000221

It says on the link...

Well, what it basically is, is a rumor that Toho was to team up with some company and the movie's climax would be a battle with Godzilla and the Devil. Tomoyuki Tanaka denied this, and Godzilla vs. Satan dove into obscurity.... BUT someone found the rumor (and not the clarification by Tanaka's part) and the news 'spread like wildfire'.

Interesting story.