From Joseph Belcher, Religious Denominations of the United State,  1865
On the Unitarian Faith:

1.The BIBLE.

They regard the sacred books of the bible as containing words of a divine revelation, miraculously made to the world. They receive as their standard, their rule of faith and life, interpreting it as they think consistency, and the princip1es of sound and approved criticism demand. They believe it is addressed to men as reasonable beings; that reverence for its records, and respect for the natures which God has bestowed on us, and which Christ came to save, make it our duty to use our understanding, and the best lights which are afforded us, for ascertaining its meaning; that God cannot contradict in one way what he records in another; that his word and works must utter a consistent language; that, if the Bible he his gift, it cannot be at war with nature and human reason; that if we discard reason in its interpretation, there is no absurdity we may not deduce from it; that we cannot do it greater dishonor than to admit that it will not stand the scrutiny of reason; that if our faculties are not worthy of trust, if they are so distempered by the fall that we can no longer repose any confidence in their veracity, then revelation itself cannot benefit us, for we have no reason left of judging of its evidences or import, and are reduced, at once, to a state of utter skepticism.

2. God.

They believe that God is one mind, one person, one undivided being; that the Father alone is entitled to be called God, in the highest sense; that he alone possesses the attributes of infinite, undivided divinity, and is the only proper object of supreme worship and love; that he yearns with a father?s tenderness and pity toward the whole offspring of Adam; that he earnestly desires their repentance and holiness, that his infinite, overflowing love led him, miraculously, to raise up and send Jesus to be their spiritual deliverer, to purify their souls from sin, to restore them to communion with himself, and fit them for pardon and everlasting life in his presence; in a word, to reconcile man to God and earth to heaven. That the gospel of Jesus Christ originated in the exhaustless and unbought love of the Father, that it is intended to operate an man, and not on God; that the only obstacle which exists; or ever has existed on the part of God, to the forgiveness of the sinner, is found in the breast of the sinner himself; that the life, teachings, and resurrection of Jesus, become an instrument of pardon, as they are the appointed means of turning man from sin to holiness, of breathing into his soul new moral and spiritual life, and elevating it to a union with the Father. That the Cross of Christ was not needed to render Christ merciful; that Jesus suffered not as a victim of God?s wrath, or to satisfy his justice, which view they think obscures the glory of the divine character, is repugnant to God?s equity, vails his loveliest attributes, and is injurious to a spirit of filial, trusting piety. Thus all, in their view, is to be referred  primarily to the boundless and unpurchased love of the Father, whose wisdom chose this method of bringing man within reach of his pardoning mercy, by redeeming him from the power of sin, and establishing in his heart his kingdom of righteousness and peace.
 

3. JESUS  CHRIST.

They believe Christ to be a distinct being from God, and subordinate to him; that he possesses only derived attributes; that he is not the supreme God himself, but his Son, and the mediator through whom he has chosen to impart the richest blessings of his love to a sinning world. They believe him to be one with God in affection, will, and purpose; not in nature, but in purpose, affection and act, through him Christians are brought near to the Father, and their hearts are penetrated with divine love. By union with him as the true vine, they are nurtured in the spiritual life. In his teachings, they find revelation of holy truth.
The question of his nature, they do not consider as important. In regard to his rank of Son, and the time at which his existence commenced, they differ. Some hold his pre-existence, others that his existence commenced at the time of his entrance into the world. At the same time, all entertain exalted views of his character and offices. In a reverence for these, they yield to no class of Christians. The divinity which others ascribe to his person, they think mat, ‘with more propriety be referred to these. “We believe firmly,” says one of their most eminent writers, “in the divinity of Christ?s mission and office; that he spoke with divine authority, and was a bright image of the divine perfections: that God dwelt in him, manifested himself through him, taught men by him, and communicated to him his Spirit without measure; that he was the most glorious display, expression, and representation of God to mankind, so that, through seeing and knowing him, we see and know the invisible Father; so that ‘when Christ came, God visited the world and dwelt with men more conspicuously than at any former period. In Christ?s words, we hear God speaking; in his miracles, we behold God acting; in his character and life, we see an unsullied image of God?s purity and love. We believe, then, in the divinity of Christ, as this term is often and properly used.”
They do not rely exclusively or chiefly on what they conceive to be the incredibility of the doctrine of Christ being God. They say they take the Bible in their hands, and sitting down to read it, as plain, unlettered Christians, and with prayer for divine illumination, find that the general tenor of its language either distinctly asserts, or necessarily implies, the supremacy of the Father, and teaches the inferior and deriv?ed nature of the Son. In proof of this, they appeal to such passages as the following: “This is life eternal, that they might know thee, the only true God, and Jesus Christ whom thou hast sent.” (John xvii. 3.) “For there is one God and one Mediator between God and man, the man Christ Jesus.” (1 Tim. ii. 5.) “My Father is greater than I.” (John xiv. 28.) “My doctrine is riot mine, but his that sent me.” ~Tbid. vii. 16.) “I spaak not of myself.” (Ibid. xiv. 10.) “I can of my ownself do nothing.” (Ibid. v. 30.) “The Father that dwelleth in me, he doeth the works.” (hid. xiv. 10.) ~‘ God hath made that same Jesus, whom ye crucified, both Lord and Christ.” (Acts ii. 86.) “Him bath God exalted with his right hand to be a prince and a Saviour.” (Ibid. v. 81.)
They appeal to such passages, and generally to all those in which
Jesus Christ is called, not God himself, but the Son of God; in which he is spoken of as sent, and the father as sending, appointing him a kingdom, “giving” him authority, giving him to be head over all things to the Church. Such passages, they contend, show derived power and authority. Again, when. the Son is represented as praying to the Father, and the Father as hearing and granting his prayer, how, ask they, can the plain serious reader, resist the conviction, that he who prays is a different being from him to whom he prays? Does one being pray to himself?
They urge that passages like those above referred to, occurring promiscuously, are fair specimens of the language in which Jesus is spoken of in the New Testament; that such is the common language of the Bible, and that it is wholly irreconcilable with the idea that Jesus was regarded by those with whom 1w lived and conversed, as the infinite and supreme God, or that the Bible was meant to teach any such doctrine. They do not find, they say, that the deportmen of the disciples and the multitudes toward Jesus, the question they asked him, and the character of their intercourse with him, indicated any such belief on their part, or any supposition that he was the infinite Jehovah. We meet, say they, with no marks of that surprise and astonishment which they must have expressed on being first made acquainted with the doctrine—an being told that he who stood before them, who ate and drank with them, who slept and waked, who was capable of fatigue and sensible to pain, was in truth, the Infinite and Immutable One, the Preserver and Governor of nature.
They contend that the passages generally adduced to prove the supreme deity of Jesus Christ, fail of their object; that without violence they will receive a different construction; that such construction is often absolutely required by the language itself, or the connection in which it stands; the most of those passages, if carefully examined, far from disproving, clearly show the distinct nature and inferiority of the Soh.
To the doctrine of three persons in one God, they abject again, its intrinsic incredibility.  They say, that they cannot receive the doctrine, because in asserting that there are three persons in the Divinity, it teaches, according to any conception they can form of the subject, that there are three beings, three minds, three conscious agents, and thus it makes three Gods, and to assert that these three are one, is a contradiction.
So too with regard to the Saviours—to affirm that the same being is both finite and infinite, man and God, they say appears to them to be a contradiction and an absurdity. If Jesus Christ possessed two natures, two wills, two minds, a finite and an infinite, they maintain that he must be two persons, two beings.
They do not reject the atonement in what they believe to be the scriptural meaning of the term. While they gratefully acknowledge the mediation of Christ, and believe that through the channel of his gospel .are conveyed to them the most precious blessings of a Father?s mercy, they object strongly to the views frequently expressed, of the connexion of the death of Christ with the forgiveness of sin. They do not believe that the sufferings of Christ were penal—designed to satisfy a principle of stern justice; for justice, say they, does not inflict suffering on the innocent in order to pardon the guilty; and besides, they believe that God?s justice is in perfect harmony with his mercy; that to separate them, even in thought, is greatly to dishonor him. They believe that however the cross stands connected with the forgiveness of sin, that connection, as before said, is to  be explained by the effects wrought on man and not on God.
They believe that in thus teaching they do not rob the gross of its power, nor take away from the sinner ground of hope. To the objection that sin requires an infinite atonement, and that none but an infinite being can make that atonement, they reply by saying, that they find in their Bibles, not one word of this infinite atonement, and besides, that no act of a finite being, a frail, sinning child of dust, can possess a character of infinity, or merit an infinite punishment; that it is an abuse of language so to speak; and further, that if an infinite sufferer were necessary to make due atonement for sin, no such atonement could ever be made, for infinite cannot suffer; that God is unchangeable, and it is both absurd and impious to ascribe suffering to him; God cannot die; and admitting Jesus to have been God as well as man, only his human nature suffered; that there was no infinite sufferer in the case; that thus the theory of the infinite atonement proves a fallacy, and the whole fabric falls to the ground. Still is not the sinner left without hope, because he leans op the original and unchanging love and compassion of the Father, to whom as the prime fountain we trace back all gospel means and influences, and who is ever ready to pardon those, who through Christ and his cross are brought t3 repentance for sin and holiness of heart and life.
Further, the Unitarians reply, that whatever mysterious offices the cross of Christ may be supposed to possess, beyond its natural power to affect the heart, it must owe that efficacy wholly to the divine appointment, and thus the nature and rank of the instrument become of no importance, since the omnipotence of God can endow the weakest instrument with power to produce any effect he designs to accomplish by it.

4. The HOLY SPIRIT.

By the Holy Spirit, they believe, is meant, not a person, but an influence; and hence it is spoken of as “poured out,” “given,” and we read of the “anointing” with the Holy Spirit, phrases, which, they contend, preclude the idea of a person. It was given miraculously to the first disciples, and gently, as the gathering dews of evening, distills upon the hearts of the followers of Jesus, in all ages, helping their infirmity, ministering to their renewal, and ever strengthening and comforting them. It is given in answer to prayer, as Christ said: “If ye, then, being evil, know how to give good gifts unto your children, how much more shall your heavenly Father give the Holy Spirit to them that ask him.” (Luke xi. 13.)

5. SALVATION

They believe that salvation, through the gospel, is offered to all, an such terms as all, by God?s help, which he will never withhold from any who earnestly strive to know an4 do his will, and lead a pure.. humble and benevolent life, have power to accept.
They reject the doctrine of native total depravity. But they assert that man is born weak, and in possession of appetites and propensities, by the abuse of which all become actual sinners; and they believe in the necessity of what is figuratively expressed by the “new birth,” that is, the becoming spiritual and holy, being led by that spirit of truth and love which Jesus came to introduce into the souls of his blowers. This change is significantly called the coming of the kingdom in the heart, without which, as they teach, the pardon of sin, were it possible, would confer no happiness, and the songs of paradise would fall with harsh dissonance on the ear.
They sometimes speak of reverence for human nature—of reverence for the soul. They reverence it as God?s work, formed for undying growth and improvement. They believe that it possesses powers capable of receiving the highest truths. They believe that God, in various ways, makes revelations of? truth and duty to the human soul; that in various ways he quickens it; kindles in it holy thoughts and aspirations, and inspires it by his life-giving presence. They believe that, however darkened and degraded, it is capable of being regenerated, renewed, by the means and influence which he provides. They believe that it is not so darkened by the fall but that some good, some power, some capacity of spiritual life, is left in it, But they acknowledge that it has need of help;  that it has need to be breathed upon by the divine Spirit. They believe that there is nothing in their peculiar mode of viewing Christianity which encourages proscription; encourages pride and self-exaltation. They believe that the heart which knows itself will be ever humble. They believe that they must perpetually look to God for help. They teach the necessity of prayer, and a diligent use . of the means of devout culture; they do not thus teach reverence for human nature in any such sense, they think, as would countenance the idea that man is  significant to save himself without God; they pray to him for illumination, pray that he will more and more communicate of himself to their souls. They teach the blighting consequences of sin. They believe that in the universe which God has formed, this is the only essential and lasting evil; and that to rescue the human soul from its power, to win it back to the love of God, of truth and right, and to obedience, to a principle of enlarged benevolence which embraces every fellow-being as a brother, is the noblest work which religion can achieve, and worth all the blood and tears which were poured out Jesus in his days of humiliation.
While they earnestly inculcate the necessity of a holy heart and a pure and benevolent life, they deny that man is to be saved by his own merit, or works, except as a condition to which the mercy of God has been pleased to annex the gift of everlasting life and felicity. They believe firmly in a future happiness for the righteous and in a punishment for the wicked.