Development for TempleOS began in 2003 after Davis suffered from a series of manic episodes that left him briefly hospitalized for mental health issues.Davis is a former atheist who believes that he can "talk with God" and that God told him the operating system he built was God's third temple. According to Davis, TempleOS is of 'Divine' intellect due to the inspired nature of the code. According to Davis, God said to create the operating system with 640x480, 16 colors display and a single audio voice. The operating system was coded in a programming language developed by Davis in C/C++ called "HolyC".