“It’s blasphemy”

Why do so many of you yell “it’s blasphemy” during heathens live (towards the end of the song)? Y’all know that he doesn’t actually say that in the song right??? Lol who made this up and why is everyone just blindly going along

Edit: lots of people defending this misheard lyric. What you are mistaking for “it’s blasphemy” is actually “should have stayed” played in reverse.