Oneness Pentecostals claim that the Godhead (the state of being God) consists of only one person who has simply manifested Himself in various ways and with different identities (as the Father, the Son, and the Holy Spirit). What does the Bible teach about the composition of the Godhead?
The Father, Son, and Holy Spirit are all referred to as “God” in the scriptures (John 6:25; Hebrews 1:8). All of the attributes of being God are found in each One. However, each One also displays a personality. Personality is defined as “the quality or fact of being a particular person; personal identity, individuality.” All three display the qualities of being an individual. The Father wills (Matthew 7:21), speaks (Matthew 3:17), knows (Mark 13:32), etc. The Son wills (John 5:21), works (John 5:17), knows (John 10:14), etc. The Holy Spirit wills (1 Corinthians 12:11), knows (1 Corinthians 2:10-11), reveals (John 16:13), etc.
The Father, Son, and Holy Spirit are separate and distinct personalities. The Godhead is composed of the Father, Son, and Holy Spirit (that is, all three are identified as God). Therefore, the Godhead is composed of three separate and distinct persons. A plurality of individuals being referred to as “one” is not unheard of in the scriptures. Jesus prayed that all believers would be “one” (John 17:20-21). Paul used the term often as well (1 Corinthians 12:12-13; Ephesians 5:31). There is a sense in which these people are one, yet they are still individuals with their own personalities. The Father, Son, and Holy Spirit are all one, but they are not one person.
Adapted from Heath Rogers