“”I capped the line-of-code count at 100,000 and God said it must be perfect, so it will never be an ugly monstrocity.
|—Terry A. Davis|
| Christ died for|
our articles about
|A multi-chef broth|
|Devil's in the details|
|The pearly gates|
Long story short, Davis was a former atheist who, after being hospitalized for mental health issues, then claimed to communicate with God and said he had heard him tell him to develop TempleOS. The OS was, according to Davis, built for "God's Third Temple". He was apparently told in these communications to create the OS with 16 colors and mono sound. It also has no network capability, and—get this—a dialect of C called "HolyC". According to him, he could communicate with God through a TempleOS program called "AfterEgypt", but no one else so far has succeeded at this. So basically, this is an OS developed by a schizophrenic that is stuck in 1990 for video and sound (despite being finished in 2003). Fortunately, TempleOS is open source (it's public domain as well), so as a mildly interesting programming project, it's not all bad.
Davis was a rather confrontational individual, and was in the habit of calling people certain racial epithets, notably referring to "CIA niggers" who Davis alleged he had killed with his car. His death, however, was met with some sadness in the hacker community—it's all too common for a hacker to have their life's work go largely unnoticed, and possibly ridiculed, so the empathy is quite understandable.
- "I was chosen by God because I am the best programmer on the planet and God boosted my IQ with divine intellect."
- "God said 640x480 16 color was a covenant like circumcision."
- "The CIA ni**ers glow in the dark, you can see em' if you're driving, you just run them over. That's what you do." 
- TempleOS.org (archived 2016-03-23)
- Man killed by train had tech following, 7 September 2018. Archived from original at The Dalles Chronicle.
- God's Lonely Programmer:Terry Davis, a schizophrenic programmer, has spent 10 years building an operating system to talk to God. by Jesse Hicks (Nov 25 2014, 7:00am) Vice Motherboard.
- TempleOS: an educational tool for programming experiments: James Sanders explores what drives one man to write an operating system for x86_64, and what the programmer's finished product looks like. by James Sanders (January 20, 2014, 11:33 PM PST) TechRepublic.
- Biography of Terry A. Davis - The greatest programmer to ever live. (January 03, 2019, 09:19 PM PST) 256Kilobytes.
- Terry Davis has died: Hacker News thread
- Comment from Terry Davis on a Hacker News thread
- Comment from Terry Davis on /r/Programming
- Comment from Terry Davis on YouTube