And yet the scripture gives the Father, Son and Holy Spirit distinct duties and roles in man's salvation. Furthermore, the three speak to each other. It makes no sense to create a division of "The Father, Son and Holy Spirit" if it wasn't real.
One God the Father, of all, who is above all, through all, and in you all.
When the fullness of time was come, God sent forth his Son, made of a woman.
For there is one God, and one mediator between God and men, the man Christ Jesus.
Which is how monotheist Jews like Paul saw the Father and the Son - which is obviously not the church fathers view, coming along some three-four hundred years after the apostles, by which time much Greek philosophic thought having shaped their thinking.
Note, the Trinitarian terminology of the creed makers is not there: “For there is one God in three coequal and coeternal persons.” Rather, the Father is the one God, the Son is the historical figure, born of a woman, stepping into history as a man, the man Christ Jesus.
Obviously, to Paul, the personal essence of the divine Being can only be ONE divine Person. The one divine Being God the Father incarnated Himself in human flesh.
Oneness Pentecostals believe that God eternally exists as God the Father, who is eternal, omnipresent, and invisible Spirit, John 4:24, incarnating Himself as the man Christ Jesus to save us from our sins (Matthew 1:18/Luke 1:35 /Hebrews 1:1-3).
Luke 1:35 And the angel answered and said unto her, The Holy Ghost shall come upon thee, and the power of the highest shall overshadow thee: therefore also that holy thing which shall be born of thee shall be called the Son of God.
Matthew 1:18 Now the birth of Jesus Christ was on this wise: When as his mother Mary was espoused to Joseph, before they came together, she was found with child of the Holy Ghost.
Hebrews 1:1-3 God, who at sundry times and in divers manners spoke in time past unto the fathers by the prophets, Hath in these last days spoken unto us by his Son … Who being the brightness of his glory, and the express image of his person…
Just one God here, the Father, revealing himself in the one mediator. Hence, no one will see three separate and distinct divine people, they will only see His express image. The invisible God made visible, Jesus Christ.