Sabellian

Part of speech: noun (n.)

A follower of Sabellius, a presbyter of Ptolemais in the third century, who maintained that there is but one person in the Godhead, and that the Son and Holy Spirit are only different powers, operations, or offices of the one God the Father.

Part of speech: adjective (a.)

Pertaining to the doctrines or tenets of Sabellius. See Sabellian, n.