Oneness Pentecostalim contains a mixture of either one or more ancient attacks on the early Church, so to know Church history is very important. By checking out the following points, we can see where Oneness Pentecostalism fits in, explaining why they will not subscribe to the Apostles’ Creed, as there are certain parts of it that they deny. The points in question are, “suffered under Pontius Pilate, was crucified, dead… rose again from the dead [bodily]… and sitteth on the right hand of God the Father Almighty” and possibly also, “the resurrection of the body”. Please bear with me as I delve into the ancient foundations of today’s Oneness Pentecostalism.
In the history of the early church, "the first great heretic" was Marcion (who died AD 100). His doctrine of God came to be known as Modalism. From Cerdo, a Syrian Gnostic, Marcion adopted the idea that there are two gods - the imperfect, wrathful war god of the OT, and the 'unknown God', the spiritual Father who revealed himself in Jesus. Marcion did not adopt the elaborate aeons of Gnosticism, but only its dualistic distinction between the Creator, or Demiurge, and the true but unknown God, the Father. Because of his dualism, which viewed the material world and physical bodies as the handiwork of the Demiurge, Marcion denied that Christ ever was truly incarnate. Thus he was also a Docetist. Marcion taught the deity of Christ but taught that he was 'the spirit of salvation' and is simply God himself. That was another reason why Marcion had to deny that Christ really suffered, for God cannot suffer and die. Marcion's successors so fully identified Christ with the Father that he appears to be merely a mode of the Father's existence, the position also taken by the Sabellians, or Modalists, of the following century.
Modalists try to explain the Trinity by viewing the three Persons as different modes of the one God. They teach no distinct individual Persons in the Godhead (as with orthodox Christianity). For the Modalist, Christ is not only God, he is the Father himself. This claims that the fundamental unity and oneness of God does not permit a second (or a third) Person can share the titles of deity (which the Bible clearly assigns to Jesus Christ and the Holy Spirit).
Modalism is a word used to try to explain the Trinity while preserving the oneness of God. Modalism frequently reappears over the centuries (right up to the present one), often found in modern circles (such as the Oneness Pentecostals) which insist on the deity of Christ but only in the sense that God reveals himself under different aspects, or modes, in different ages - as the Father in creation and the giving of the Law; as the Son in Jesus Christ; as the Holy Spirit after Christ's ascension. In so doing, Modalists 'lose' the role of Jesus representing us to the Father. It is a form of Docetism, claiming that the Son, as Christ, only appeared to be human. Theologically, the teaching then becomes a Christ who was fully God, but who only appeared to be a man - which renders the biblical doctrine of Christ fully representing humanity because he was fully human himself null and void.
Today, Oneness Pentecostalism says Christ is God, who can also appear as the Father or the Holy Spirit. The problem with this is seen when we consider how Christ, the man, prayed to His Father in Heaven (also with the Holy Spirit present as a dove at Christ’s baptism). A more serious problem with such Modalism is that it negates the Bible statement that Jesus is our advocate with the Father as in 1 John 2:1.
Trinitarian Christians certainly do not accept Modalism or its modern counter-part, Oneness Pentecostalism, which cannot accept all parts of the Apostles’ Creed. The book below, from which I have culled these points, is excellent in informing us of such developments, for our protection so that we may identify modern-day versions. Heresies & Orthodoxy in the history of the Church, Harold O.J. Brown (Hendrickson 1998)