The Second Coming has long been rumored to be the plot of the third and final season. Apparently, it was meant to be the plot of a hypothetical follow-up book by Gaiman and Terry Pratchett, but that never materialized.
"It was tough, bittersweet for sure. Because this has been our life for four seasons but over six years... So it was hard but I think we stuck the landing. This season, the fourth season, is the best yet."