User blog comment:Twilight Despair 5/A (Cure) or whatever for the Mark of Cain/@comment-71.191.75.32-20150225212357/@comment-3481504-20150226014721

So, God, then? I highly doubt that the writers will have God intervene in this, especially not in person. I don't know what the 'source' could mean here, Lucifer makes sense, but I don't see Lucifer appearing in any episode after "Swan Song," seeing as that's the way Kripke intended it. The source could very well mean Adam, being the source of humankind.