For anyone unfamliar:

TempleOS (formerly J Operating System, LoseThos, and SparrowOS) is a biblical-themed lightweight operating system (OS) designed to be the Third Temple prophesied in the Bible. It was created by American programmer Terry A. Davis, who developed it alone over the course of a decade after a series of manic episodes that he later described as a revelation from God.

Davis began developing TempleOS circa 2003. One of its early names was the "J Operating System" before renaming it to "LoseThos", a reference to a scene from the 1986 film Platoon. In 2008, Davis wrote that LoseThos was "primarily for making video games. It has no networking or Internet support. As far as I'm concerned, that would be reinventing the wheel". Another name he used was "SparrowOS" before settling on "TempleOS". In mid-2013, his website announced: "God's temple is finished. Now, God kills CIA until it spreads [sic]."

Davis died after being hit by a train on August 11, 2018.

TempleOS was written in a programming language developed by Davis as a middle ground between C and C++, originally called "C+" (C Plus), later renamed to "Holy C", possibly a reference to the Holy See. It doubles as the shell language, enabling the writing and execution of entire applications from within the shell. The IDE that comes with TempleOS supports several features, such as embedding images in code. It uses a non-standard text format (known as DolDoc) which has support for hypertext links, images, and 3D meshes to be embedded into what are otherwise standard ASCII files; for example, a file can have a spinning 3D model of a tank as a comment in source code. Most code in the OS is JIT-compiled, and it is generally encouraged to use JIT compilation as opposed to creating binaries. Davis ultimately wrote over 100,000 lines of code for the OS.

From Wikipedia