“Eighth theist” and “eight theist” are puns for “atheist.” “Eighth-Theist (n.) - Someone who only believes in God 12-1/2% of the time” was cited on Twitter on June 20, 2011.
   
“I only believe in 12.5% of everything the Bible says. Which makes me an eighth theist” was posted on Reddit on May 14, 2016.
   
 
Twitter
Stephen Simmons
‏@stephen_simmons
Eighth-Theist (n.) - Someone who only believes in God 12-1/2% of the time.
8:01 PM - 20 Jun 2011
   
Twitter
Emily Khilfeh
‏@khilfish
From my sister: I used to believe in seven, but now I’m an eight-theist.
6:27 PM - 1 Apr 2013
 
Twitter
ShaniceMonica
‏@monica_shanice
One of my great-grandparents believed in God, but the other seven didn’t Which makes me an eighth theist #lol
1:12 PM - 4 May 2016
 
reddit
I only believe in 12.5% of everything the Bible says.
submitted May 14, 2016 by mapleleafraggedy
Which makes me an eighth theist.
 
Twitter
CorinneRosa
‏@corinne_rosa
I only believe in 12.5% of everything the Bible says. Which makes me an eighth theist. #lmao
11:52 PM - 14 May 2016
 
Twitter
IMA WARIO!
‏@THEJackBiggs
I only believe in 12.5% of everything the Bible says. Some would say I’m an eight theist.
10:14 AM - 15 May 2016