The definition of a Christian is a believer in the Christ, the Messiah, the second Person of the triune God, Emmanuel -—GOD with us, as revealed in the Holy Bible. The book of Mormon has some lovely passages in it, some of which are true, but anything in it that contradicts The Holy Bible, is a lie from the pit of Hell. If you recall, the Serpent in the Garden of Eden, spoke just enough truth to beguile Eve. That’s one of his specialties -— perverting the WORD of God. I don’t know if you are an adult convert, or were born into the Mormon church (in which case you have been indoctrinated from birth). In such a case, one could almost not blame you for your beliefs, but since the Holy Bible is readily available to you, and I assume you’ve read it, you are without excuse. Your eyes have been blinded, but if you diligently seek Him, through the Holy Bible, He will be found!
There is no requirement that a Christian believe in Emperor Costantines dictated ‘homousis’ triune God.
Neither Origin nor Tertullian believed in the later concept of the Trinity (although Tertullian likely coined the term, he did not use it in a homousis manner) and both were Christian.
In-fact even Christ himself did not believe in the Trinity as evident in the bulk of biblical passages.