Unitarians have held various beliefs as described below. In the main they regard Christ as subordinate to the Father. Though they admit His pre-existence, the supernatural nature of His character and mission, His role as creator and that He should be honored, they do not accept worshipping Christ as a supreme being. Seventh-day Adventists are not unitarian.
"At first the Unitarians moved only to Arianism, which “did not lessen for them their implicit faith in his [Christ’s] revelation or their recognition of the beauty and glory of his divine character.” 44 George Willis Cooke, Unitarianism in America, p. 15. He defines the Arian position by saying that they insisted on the language of the New Testament; they regarded the Son as subordinate to the Father, as in the ancient family, but they believed in Christ's pre-existence. His supernatural character and mission, that He was the creator, or that the world was created “by means of the spirit that was in him, and that every honor should be paid him except that of worshipping him as the Supreme Being.” (Ibid., p. 56.) The Unitarians denied (a) the depravity of human nature, (b) the worship of Christ a[s] God, (e) the substitutionary atonement as the means of salvation. But a later period of radicalism brought in the new theory that the spiritual message is “inward,” and not outward, “directly to the soul of a man,” and not through the mediation of a person or a book. 45 Ibid., p. 199. Although tolerating all shades of opinion, the Unitarian Church moved far beyond the liberalism of Channing’s day. The human emphasis in place of a supernatural message soon channeled Unitarian zeal and idealism into humanitarian enterprises. The ideals of Transcendentalism, expressed by some of the most noted literary lights of New England, were of Unitarian origin." Prophetic Faith of Our Fathers, Vol. 4, 30.
Note what the Bible says on the subject of Christ being inferior.
Philippians 2:6 "Who, being in the form of God, thought it not robbery to be equal with God:"
John 5:23 "That all men should honour the Son, even as they honour the Father. He that honoureth not the Son honoureth not the Father which hath sent him."
1 John 2:23 "Whosoever denieth the Son, the same hath not the Father: (but) he that acknowledgeth the Son hath the Father also."
I and my Father are one.” {ST November 27, 1893, par. 4} With what firmness and power he uttered these words. The Jews had never before heard such words from human lips, and a convicting influence attended them; for it seemed that divinity flashed through humanity as Jesus said, “I and my Father are one.” The words of Christ were full of deep meaning as he put forth the claim that he and the Father were of one substance, possessing the same attributes. The Jews understood his meaning, there was no reason why they should misunderstand, and they took up stones to stone him. Jesus looked upon them calmly and unshrinkingly, and said, “Many good works have I showed you from my Father; for which of these works do ye stone me?” {ST November 27, 1893, par. 5} The Majesty of heaven stood, calmly assured, as a god before his adversaries. Their scowling faces, their hands filled with stones, did not intimidate him. … He stood before them undaunted. Why did not the stones fly to the mark?—It was because divinity flashed through humanity, and they received a revelation, and were convicted that his were no common claims. Their hands relax and the stones fall to the ground. His words had asserted his divinity, but now his personal presence, the light of his eye, the majesty of his attitude, bore witness to the fact that he was the beloved Son of God. {ST November 27, 1893, par. 6} Had the Pharisees misunderstood his words, he could and would have corrected their wrong impression. He could have told them that he was no blasphemer, although he had called himself the Son of God, and that his words need not necessarily mean that he had invested himself with divine prerogatives, and made himself equal with the Father. But he made no such statement. The impression they had received was the very impression he desired to make.—Signs of the Times, November 27, 1893, par. 7} Italics added.
James White wrote an article on the equality of Christ with His Father in the 1870s, in which he deplored the Unitarian position that made Christ an inferior being. Note a few thoughts below, and then read the entire article.
“Paul affirms of the Son of God that he was in the form of God, and that he was equal with God. "Who being in the form of God thought it not robbery to be equal with God." Phil. 2 : 6. The reason why it is not robbery for the Son to be equal with the Father is the fact that he is equal. If the Son is not equal with the Father, then it is robbery for him to rank himself with the Father. … We may look upon the Father and the Son before the worlds were made as a creating and law administering firm of equal power. Christ did not then rob God in regarding himself equal with the Father. Sin enters the world and the fall occurs. Christ steps out of this firm for a certain time, and takes upon himself the weakness of the seed of Abraham, that he may reach those who are enfeebled by transgression. ... we call attention to it to guard the people against that terrible heresy that takes from our all-conquering Redeemer his divine power. {RH November 29, 1877}—James White, “Christ Equal With God,” {RH November 29, 1877} (Read The Rest Of James White's Article)