If you haven’t seen this short 3 minute ‘featurette’ where Mike Flannagan explains the impetus for writing the show “Midnight Mass”, it’s worth your time.
Most importantly, he discusses how he started writing the script in 2010 (so it took 11 years to become what it became); that he thought it would be a movie first until he realized how deep the story should be; and that it came from a scary “what if” question he had in his own life.
This short conversation is a great look into the mind of a writer (even if you haven’t watched the show and might not even intend to because horror scares you….the lessons are all still evident in this conversation).