You deny the person of God the Father and the person of God the Holy Spirit and falsely assert that Jesus only is all three: hence the name Oneness.
The "Oneness" teaching rejects the Trinitarian concept of three separate and distinct persons in the Godhead and claims instead that Jesus alone is the one God of the Bible. It is this Jesus who reveals himself in different forms, or "modes", at different times, as Father, Son, or Holy Spirit. All three are simply the same person, Jesus, appearing in the "mode" appropriate to the occasion.
This counterfeit Christ is both Father and Son at the same time. Although He is spoken of as a "man", He is in truth, unlike any other man who has ever lived, in that He has two separate natures, one human, one divine. He was confined to earth as a man, and yet at the same time, in Heaven and omnipresent as God.
As the "human" Jesus He worships and prays to the divinity within Himself.
On the cross only His human nature "died", since in His second divine nature, as God, He could not die.
The temptation of Jesus in the wilderness is made into a total farce. They say that although His human nature was tempted, He could not sin at all because of His second divine nature.
Because of their belief in only one person as God, these churches usually also insist that baptism "in the name of the Father, Son and Holy Spirit", (Matt 28,19), is not valid. To be acceptable to their "oneness" God (and to these men) it must be "in the name of Jesus" (only). Anyone baptised in the threefold name of "Father, Son and Holy Spirit", must renounce that baptism and be rebaptised with the right words said over them, before they can be regarded as really baptised.
However, even then, salvation is not complete and the new birth is not regarded as accomplished until the person concerned has spoken in tongues, as evidence of their "Baptism with the Holy Spirit". For honest hearts, this "Oneness" doctrine is sadly lacking in logic.
For eyes and ears open to simple Bible truth, this Jesus simply cannot be a REAL MAN. The Oneness churches do pay lip service to the word "man" in relation to Jesus, but no matter how we attempt to rationalise this, their two natured Jesus is actually a God, very different to other men. Their Jesus is in reality, a modern version of that first century spirit of Antichrist, which is the subject of John's first and second epistles.
John uses hard words about this. So must we. But let us be careful to use those words from John's epistle reluctantly, cautiously, and in love, without hatred or bitterness.
To put it simply, using John's words, the Oneness teaching about the person of Jesus, IS A LIE which denies both the real meaning of the relationship between Father and Son, and the true identity of the Christ. (1 John 2,22)
John says very bluntly that no such lie is of the Truth, (1 John 2,21), and that any spirit which insists that Jesus is not really a man, is NOT the Spirit of Truth, but is instead, the Spirit of Error. (1 John 4,6)
Another Jesus and another gospel. Come out of the error into the truth.
Only Jesus?
The Gospel is The Death The Burial and Resurrection of Jesus Christ. Who is All the Fullness of the Godhead Bodily.
How is it a different Gospel? I believe you have some very twisted views on what Pentecostals believe, and don't appreciate all the negativity and name calling against it. I believe we should think before we type. We will be judged on this. We are to love each other. This topic is getting very heated and I think it should take a rest for the time being. Before someone does or says something that they will regret when judgment day comes.