Known by many names; Abba, Adonai, or even simply as God. Whichever name He is known by, His true name YHVH (or sometimes YHWH) is never spoken out loud. Mortals attempting to speak His name in any language except for Celestial hear a static-like sound coming from their mouth, the name being one which no mortal language can replicate.
Devotion: Worshipers of YHVH must do one of the following in order to increase Devotion with Him; prayer to Him at the end of the day, slay a demon, or help someone recover from injuries.