The history of Christian doctrine shows that the whole emphasis on "Oneness" comes from Augustine and the Western Church. Latin was never able to properly translate Greek terms regarding the Trinity, so it stuck to the one God. Persona, the Latin name for hypostasus, doesn't mean "person" as we have translated it into English. Persona is a mask or actor. The three hypostasis are NOT wearing masks, or acting, they are authentic, honest and real. The western church falls short of answering the Biblical question of who God is, although fortunately, through the ages, most western church did come to understand the 3 in 1. Unfortunately the Oneness Pentecostals are completely lost as to the real nature of God.
This is not to say God is not One, of course he is! But the Greek Church, particularly the Cappadocian Fathers, started with the Threeness of God. Rather than "persons" in Latin, the began with 3 hypostasis, and then moved to one being, or ousia. So, by starting with the threeness of God, and moving to the being of God, you don't lose the three separate hypostasis, namely the Father, the Son and the Holy Spirit. Plus, you can see at a glance that the "being" of the three is the same.
In fact, God is love. If you only have one Hypostasis, you totally lose that quality. There is no object to receive the love of God, within Oneness. 1 John 4:8, 16, proclaims "God is love." Three hypostasis love each other. There is never a time when God is not completely loving, and out of this, came God's love for humanity. The Father loves the Son, the Son loves the Father. The Father loves the Holy Spirit, the Holy Spirit loves the Son, which is mutual, and the Holy Spirit loves the Father. There is always love. Without separate hypostasis, no one is loving anyone. A single being, in oneness, does not have anyone to love. Therefore God is NOT love, nor will God love humans, because love has no object within the oneness to love.
I have always looked at Oneness theology as being made up by people without a solid understanding of Greek and Hebrew, and a weak attempt to try and answer the questions of who God is. They start with the Shema in Deuteronomy 6, and then continue down a blind ally that is meaningless. I don't say this to insult people, but rather to gently show these people how lost they are. Like the video on page 1 of this thread, I also take Trinitarian belief to be salvic. Which means that Oneness is wrong, and the person is not saved.
We have been friends for 40 years with a man that we met in a regular Pentecostal Church. They believed in the Trinity. Many years later, he was trying to trip me up on the Trinity, and prove there was only one God. I hadn't been to seminary, at that time, yet, but I had studied the Trinity. I spent a lot of time arguing this with him, using Scripture to back myself up. He was dead stuck on Oneness, and went on to write a whole commentary in the Bible from a Oneness perspective. Except he had poor grammar, and the worst spelling. I tried to help him with his English, but gave up, overwhelmed by the English mistakes. I have literally never seen anyone with such a poor understanding of English. Yet, he published that commentary, and set himself up as a teacher and preacher, and many followed him. It's beyond my understanding why anyone would follow someone not just with bad writing skills, but also with a total disregard for theology. So, yes, it is important how and what you write. But if a Oneness Pentecostal had perfect English, but held onto bad theology, we still need to walk away from terrible theology.