Christians who believe in Oneness Theology use the word "ONE" to describe God's essence of Being because the scriptures are filled with references to the One true God as "the Holy One" rather than an alleged "Holy Three." Furthermore, the divine Name that God has chosen for Himself is Yahweh which literally means, "The Self Existent One" (See Strongs Concordance of the Bible). God never says that He is the Self Existent Three!
The full Trinitarian Creed was developed about 300 years after the New Testament Scriptures were already written. Therefore the historical evidence proves that the majority of the earliest Christians of the first few centuries knew no such doctrine of a trinity of three coequal and coeternal divine persons of an alleged three person deity.
Christian scholars and historians admit that the fully developed Trinitarian Theology that was formulated in the fourth and fifth centuries by the Roman Catholic Church was not solidly established by the Christians of the first three hundred years of Christian history.
The Encyclopedia of Religion And Ethics records: “At first the Christian Faith was not Trinitarian ... It was not so in the apostolic and sub-apostolic ages, as reflected in the New Testament and other early Christian writings."
Dr. A. T. Hanson affirmed that the Trinity doctrine evolved within the first few centuries of Christian history: “No responsible NT scholar would claim that the doctrine of the Trinity was taught by Jesus or preached by the earliest Christians or consciously held by any writer of the NT. It was in fact slowly worked out in the course of the first few centuries in an attempt to give an intelligible doctrine of God.” (The Image of the Invisible God, SCM Press, 1982, Dr. A. T Hanson, Professor of Theology University of Hull)
The New Catholic Encyclopedia admits: "The formulation 'one God in three Persons’ was not solidly established, certainly not fully assimilated into Christian life and its profession of faith, prior to the end of the 4th century ... Among the Apostolic Fathers, there had been nothing even remotely approaching such a mentality or perspective."
We know that the apostles of the first century Christian Church were saved but they, like Oneness Pentecostal Christians, never professed a belief in three coequal and coeternal divine spirit persons of an alleged trinity. If the apostles were saved without the Trinitarian Creed, it makes sense to believe that Christians who believe in the full deity of Christ without adding the unscriptural creedal language of Trinitarianism are also saved. Christians are commanded to not judge others by unscriptural standards that were never taught in God's Word. Yet true Christians are everywhere being persecuted because they refuse to believe that we must turn to the creeds of the Roman Catholic Church to find the true faith that was already delivered unto the saints in the first century Christian era.