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.
And yet the 'three witnesses' give TESTIMONY to it.
An 1830 statement titled "Testimony of Three Witnesses"—one statement signed by three men rather than three separate statements—was published at the end of the first edition of the Book of Mormon:
Be it known unto all nations, kindreds, tongues, and people, unto whom this work shall come: That we, through the grace of God the Father, and our Lord Jesus Christ, have seen the plates which contain this record, which is a record of the people of Nephi, and also of the Lamanites, his brethren, and also of the people of Jared, who came from the tower of which hath been spoken. And we also know that they have been translated by the gift and power of God, for his voice hath declared it unto us; wherefore we know of a surety that the work is true. And we also testify that we have seeen [sic] the engravings which are upon the plates; and they have been shewn unto us by the power of God, and not of man. And we declare with words of soberness, that an angel of God came down from heaven, and he brought and laid before our eyes, that we beheld and saw the plates, and the engravings thereon; and we know that it is by the grace of God the Father, and our Lord Jesus Christ, that we beheld and bear record that these things are true. And it is marvellous [sic] in our eyes. Nevertheless, the voice of the Lord commanded us that we should bear record of it; wherefore, to be obedient unto the commandments of God, we bear testimony of these things. And we know that if we are faithful in Christ, we shall rid our garments of the blood of all men, and be found spotless before the judgment-seat of Christ, and shall dwell with him eternally in the heavens. And the honor be to the Father, and to the Son, and to the Holy Ghost, which is one God. Amen.
They must have gotten the concept from the Book of Mormon...
Book of Mormon:
Now Zeezrom said: Is there more than one God? And he answered, No. (Alma 11:28-29)
...and be arraigned before the bar of Christ the Son, and God the Father, and the Holy Spirit, which is one Eternal God, to be judged according to their works, whether they be good or whether they be evil. (Alma 11:44)
...doctrine of Christ, and the only and true doctrine of the Father, and of the Son, and of the Holy Ghost, which is one God, without end. Amen. (2 Nephi 31:21)
...praises with the choirs above, unto the Father, and unto the Son, and unto the Holy Ghost, which are one God, in a state of happiness which hath no end. (Mormon 7:7)
...power of God; and the Son, because of the flesh; thus becoming the Father and Son--And they are one God, yea, the very Eternal Father of heaven and of earth. And thus the flesh becoming subject to the Spirit, or the Son to the Father, being one God, (Mosiah 15:3-5)
...of Jared, that whoso should possess this land of promise, from that time henceforth and forever, should serve him, the true and only God, or they should be swept off when the fulness of his wrath should come upon them. (Ether 2:8)
"Behold, I am Jesus Christ the Son of God. I created the heavens and the earth, and all things that in them are. I was with the Father from the beginning. I am in the Father, and the Father in me; and in me hath the Father glorified his name." (3 Nephi 9:15)
"And again the Lord called others, and said unto them likewise; and he gave unto them power to baptize. And he said unto them: On this wise shall ye baptize; and there shall be no disputations among you. Verily I say unto you, that whoso repenteth of his sins through your words and desireth to be baptized in my name, on this wise shall ye baptize them--Behold, ye shall go down and stand in the water, and in my name shall ye baptize them. And now behold, these are the words which ye shall say, calling them by name, saying: Having authority given me of Jesus Christ, I baptize you in the name of the Father, and of the Son, and of the Holy Ghost. Amen. And then shall ye immerse them in the water, and come forth again out of the water. And after this manner shall ye baptize in my name; for behold, verily I say unto you, that the Father, and the Son, and the Holy Ghost are one; and I am in the Father, and the Father in me, and the Father and I are one...And thus will the Father bear record of me, and the Holy Ghost will bear record unto him of the Father and me; for the Father, and I, and the Holy Ghost are one." (3 Nephi 11:22-27, 36)
Sorry; but the 'bulk of passages' will HAVE to be shown; instead of merely claimed to exist; since your own QUAD has the words:
"Let US make man in OUR image."
I do not know how this resonates in the LDS trained mind; but to most any other person who reads it must surely come away with the fact that there are at LEAST two entities being referred to here.