The author is a distinguished public intellectual/author, and he offers Interreligious guidance for the perplexed, from an Islamic Unitarian perspective:

"Dr. Laurence B. Brown, MISGOD’ED A ROADMAP OF GUIDANCE AND MISGUIDANCE WITHIN THE ABRAHAMIC RELIGIONS (2007) QV in LThg. ISBN: 1-4196-8148-6

This is the first of two books designed to analyze the scriptural foundation of the three Abrahamic faiths of Judaism, Christianity and Islam. In doing so, I hope to help readers identify the valid links in the chain of revelation and differentiate the truth of God’s guidance from the falsehoods of human corruption.

The methodology and conclusions drawn herein are founded upon respected scholastic research—as well as common sense. With regard to methodology, there is no substitute for shaking the trees from which different faiths claim to harvest fruits of sacred knowledge, and seeing what falls out.

Analysis of the foundation of Christian doctrines has become very popular recently, and many respected scholars have discovered that much of Christian canon derives from non-biblical sources. The real shock is that many of these non-biblical sources actually contradict the teachings of Jesus Christ. For example, nowhere in the foundational manuscripts of the New Testament does Jesus Christ refer to himself as a literal Son of God. He identifies himself as the Son of Man eighty-eight times, but not once as a Son of God in a literal, begotten and not made sense. Nor does Jesus Christ espouse the Trinity. In fact, in three separate passages he teaches the exact opposite, defining God as One—never as a Trinity. "

Also notes that Jesus never claimed to have died for Sins. [8]
He fairly argues that "The Jewish attributes of God carry over into Christian definitions as well, although God’s One-ness suffered in the transformation from the strict monotheism of the apostolic age to the mysticism of the Trinity. Coming out of one corner is the Trinitarian understanding of three entities in One—a concept repudiated by Unitarian challenges.
Indeed, how could substances with opposite polarities (i.e., mortality/immortality; with beginning/without beginning; mutable/immutable, etc.) possibly exist in one entity? Why did Jesus Christ ascribe his miraculous works exclusively to God and not to any divinity
of his own, if he was in fact a partner in divinity? And why did he testify to having received his gifts from God if he and the Creator are co-equal? (For relevant verses, see John 3:35, 5:19–23, 5:26–27, 10:25, 13:3, 14:10, Acts 2:33, 2 Peter 1:17, Rev 2:26–27.). Brown points out that the Trinitarian God resembles Zeus and begs idolatry: "Michelangelo’s ceiling fresco in the Sistine chapel. The fact that this image is not at all dissimilar to the ancient Greek representation of Zeus has not gone unnoticed, and many
object, and not just on the basis of the second commandment (which forbids “any likeness of anything that is in heaven above, or that is in the earth beneath, or that is in the water under the earth . . .”(Exodus 20:4–5)

This work also examines the teachings of Arius--63ff--with the caution that none of his voluminous writings survived Trinitarian persecution. "The concept that God provided revelation without clarifying His Own nature
grates painfully against our innate understanding of God as all-merciful, providing clear guidance to all humankind. Standard Trinitarian response? That people would believe if only they understood. Standard Unitarian response? Nobody understands the Trinity—nobody. That’s why it’s a
religious mystery."

This mystery, of course, is a stumbling block to both Faith and Belief, as well as Knowledge or clarity. "“The only way a person can believe is to have faith” (i.e., the only way to believe is to believe). But if blind, unthinking faith is the methodology God bids us to follow, why
does He command us to reason (“‘Come now, and let us reason together,’ says the Lord . . .” Isaiah 1:18)?103(EN)". {102} Brown notes the fact that Trinitarians claim to somehow "believe" in what remains utter mystery, and for Clerics.

Dr Brown inserts imperial and colonial conversion data into the investigation. The doctrine of Trinity is responsible for Medieval and Spanish inquisitions, eight waves of Crusades, and over twelve million natives who died under torture during colonialism. Pope IX instituted the Inquisition in 1231, but "could not stomach the sin of torture. It took twenty years for a pope to shoulder the responsibility...". Ironically, that was Pope Innocent ("cough, cough") IV, who authorized torture in 1252. {104}

As is often cited by Church historians, the formal doctrines of the Trinity and divine sonship both sprang from the Council of Nicaea, and were incorporated into the Nicene Creed—“A profession of faith
agreed upon, although with some misgivings because of its non-biblical terminology, by [largely un-named] bishops at Nicaea I (325 CE)." Brown provides a detailed and academically robust animadversion on what became the creedal defense of the doctrine of the Trinity against the Unitarian Arius. {111} In 381, fifty six years later, the Doctrine was ratified. Most of the previous participants in the Council did not reappear, but Emperor Constantine took personal charge of the Council of Nicea. {The venue was his favorite Nympheum}. He was not a member of the Church, but had political needs. Even so, he failed to resolve the Unitarian-Trinitarian controversies.

Dr. Brown cites Bart D. Ehrman, author of The New Testament: A Historical Introduction to the Early Christian Writings and perhaps the most authoritative contemporary voice to remind us that the Trinity was not widely accepted. Dr. Wrede is quoted limning the differences between the teachings of Paul and Jesus. Dr. Johannes Weiss is quoted “Hence the faith in Christ as held by the primitive churches" suggesting that Paul was preaching "a new type of religion". Baigent and Leigh summarize the fact that this new religion had "less and less to do with its supposed founder".
{120}

Here, Dr Brown circles back to the fifty-six year gap between Councils.

...persecutions of Unitarians. Correctly pointing out that the burning of heretics was not only an indulgence of the punitive arm of the Roman Catholic Church. The early Protestant church persecuted heretics with the same enthusiasms, perhaps without the nicety of obtaining forgiveness for the sin of torture. "Michael Servetus was condemned to this horrific fate by none other than John Calvin, one of the founders of Protestantism. Despite the fact that Servetus, a Spaniard, possessed a letter of safe conduct, he was executed in Geneva for the alleged crime of being an Anabaptist and a Unitarian." {309,FN 51.} ( )