We don't have synonyms for tetratheist yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are tetratheism.
(n) :
(Christianity) The belief that there are four elements in the Christian Godhead—the three hypostases (Father, Son, Holy Spirit) of the Trinity and a divine essence out of which each of these originates.
(n) :
(Christianity) The belief that there are four elements in the Christian Godhead—the three hypostases (Father, Son, Holy Spirit) of the Trinity and a divine essence out of which each of these originates.