Sacred writing has always been a special category of script, obeying its own rules and subject to different constraints than most other types of (secular) writing. In the world of sacred words, humans may write, but the divinity inspires, leads, guides and impels the hand holding the quill. Sometimes, the divine takes full responsibility for the writing, like the writing on the wall at Belshazzar’s feast recounted in the Book of Daniel of the Old Testament: mene, mene, tekel, upharsin. Belshazzar’s kingdom is doomed.
God writes not only on walls, but in the sky as well. Dante Alighieri may have been the first to have divine words float in the heavens like the smoke of a skywriting plane. In Canto 18 of Paradiso, he witnesses the Latin words ‘DILIGITE IUSTITIAM QUI IUDICATIS TERRAM’ (Love justice you who rule the world) suspended in space in the heavenly sphere of Jupiter. The words are embodied in the sense that they are made up of the heavenly bodies of the souls inhabiting the sphere, who cluster together to create the script.
When God doesn’t write or cause any writing to be inscribed on surfaces or ether, scribes take up the challenge of creating sacred spaces for divine writing. This can take many forms. In the Jewish tradition, scribes often use gold leaf when writing the unpronounceable/unwritable name of G-d in the Torah. In the medieval Christian tradition, scribes used special abbreviations known as nomina sacra (sacred names) for words associated with the triune God. The abbreviation was signalled by a line written over the letters : ΘΣ for God (Θεός), IC XC for Jesus Christ (Ἰησοῦς Χριστός) or SPS SCS for the Holy Spirit (Spiritus Sanctus).
Most types of sacred writing practices have disappeared in the modern period. The only one to have survived that I can think of is that of capitalising the first letter in the name of God. This may arguably be more a case of personalising the name of God than preserving a form of nomen sacrum, but the distinction between upper-case and lower-case may also point to one of the last scriptural sacred spaces available.