The rendering of "the Word was God" in Bibles such as the King James Bible (published in 1611 by King James of England), the Catholic Douay (published 1582 in Rheims, France), Latin Vulgate (published in 405 C.E. by Jerome), etc. does not have "leg to stand on". And why ?
Because the translators were already prejudiced towards the Trinity when these Bible were written, unwilling to keep bias "out of the picture". Koine Greek, in which the last 27 books of the Bible were written (or the Christian Greek Scriptures, also called "the New Testament"), had a definite article such as "the", but did not have an indefinite article that left words as uncertain, such as "the man" that identifies a specific person, while "a man" leaves things unclear.(During the 15th to the 17th centuries, it was considered a crime to not accept the trinity, causing many to be burned on stakes for rejecting the trinity; see John Foxe's Book of Martyrs, published in 1554 C.E. in Latin, as well as Jean Crespin's Book of Martyrs, published also in 1554 C.E. in French)
At John 1:1, the apostle John, to ensure that there is no ambiguity, places a definite article before "Word" or "the Word" both times to identify who he is specifically speaking of, and a definite article before the first instance of "God" or "the God", but does not do so in the last instance of "god", leaving it indefinite or "a god".
The Christian Greek Scriptures was later translated from Koine Greek into other languages, such as Syriac, Latin and Coptic (spoken in Egypt, in which the Coptic Orthodox Church in Egypt has between 6 to 11 million members), but of these languages, only Coptic has an indefinite article, and is very similar to English in its grammar.
Regarding the earliest Coptic translations of the Bible, The Anchor Bible Dictionary says: “Since the [Septuagint] and the [Christian Greek Scriptures] were being translated into Coptic during the 3d century C.E., the Coptic version is based on [Greek manuscripts] which are significantly older than the vast majority of extant witnesses.”
Scholar Thomas O. Lambdin (leading scholar of Semitic and Egyptian languages, born in 1927 and died in May 2020) in his work Introduction to Sahidic Coptic, says: “The use of the Coptic articles, both definite and indefinite, corresponds closely to the use of the articles in English.”
Hence, the Coptic translation supplies interesting evidence as to how John 1:1 would have been understood back then. What do we find ? The Sahidic Coptic translation uses an indefinite article with the word “god” in the final part of John 1:1.
Thus, when rendered into modern English, the translation reads: “And the Word was a god.” Evidently, those ancient translators realized that John’s words recorded at John 1:1 did not mean that Jesus was to be identified as Almighty God. The Word was a god, not Almighty God.
The text of John 1:1 in Sahidic Coptic reads: "In the beginning existed the Word
and the Word existed with
the God and a god was
the Word".(SAHIDIC COPTIC TEXT; P. CHESTER BEATTY-813; WITH INTERLINEAR TRANSLATION, at the Chester Beatty Library, Dublin, Ireland)
Your unitarian argument is completely bogus and has no substance as proven by all there real N.T. Greek Scholars, Grammarians, Linguistic Experts and Theologians below.
Omission of the article with "Theos" does not mean the word is "a god." If we examine the passages where the article is not used with "Theos" we see the rendering "a god" makes no sense (Mt 5:9, 6:24; Lk 1:35, 78; 2:40; Jn 1:6, 12, 13, 18; 3:2, 21; 9:16, 33; Ro 1:7, 17, 18; 1 Co 1:30; 15:10; Phil 2:11, 13; Titus 1:1). The "a god" position would have the Jehovah's Witnesses translate every instance where the article is absent. As "a god (nominative), of a god (genitive), to or for a god (dative)." But they do not! "Theou" is the genitive case of the SAME noun "Theos" which they translate as "a god" in John 1:1. But they do not change "Theou" "of God" (Jehovah), in Matthew 5:9, Luke 1:35, 78; and John 1:6. The J.W.’s are not consistent in their biblical hermeneutics they have a bias which is clearly seen throughout their bible.
Other examples-In Jn.4:24 "God is Spirit, not a spirit. In 1 Jn .4:16 "God is love, we don’t translate this a love. In 1 Jn.1:5 "God is light" he is not a light or a lesser light.
WHAT DO GREEK SCHOLARS THINK ABOUT JEHOVAH'S WITNESS TRANSLATION OF JOHN 1:1?
Dr. J. J. Griesback: "So numerous and clear are the arguments and testimonies of Scriptures in favor of the true Deity of Christ, that I can hardly imagine how, upon the admission of the Divine authority of Scripture, and with regard to fair rules of interpretation, this doctrine can by any man be called in doubt. Especially the passage John 1:1 is so clear and so superior to all exception, that by no daring efforts of either commentators or critics can it be snatched out of the hands of the defenders of the truth."
Dr. Eugene A. Nida (Head of the Translation Department of the American Bible Society Translators of the GOOD NEWS BIBLE): "With regard to John 1:1 there is, of course, a complication simply because the NEW WORLD TRANSLATION was apparently done by persons who did not take seriously the syntax of the Greek". ( Bill and Joan Cetnar Questions for Jehovah's Witnesses "who love the truth" p..55
Dr. William Barclay (University of Glasgow, Scotland): "The deliberate distortion of truth by this sect is seen in their New Testament translations. John 1:1 translated:'. . . the Word was a god'.a translation which is grammatically impossible. it is abundantly clear that a sect which can translate the New Testament like that is intellectually dishonest. THE EXPOSITORY TIMES Nov, 1985
Dr. B. F. Westcott (Whose Greek text is used in JW KINGDOM INTERLINEAR): "The predicate (God) stands emphatically first, as in 4:24. It is necessarily without the article . . . No idea of inferiority of nature is suggested by the form of expression, which simply affirms the true Deity of the Word . . . in the third clause `the Word' is declared to be `God' and so included in the unity of the Godhead." The Gospel According to St. John (Eerdmans,1953- reprint) p. 3, (The Bible Collector, July-December, 1971, p. 12.)
Dr. Anthony Hoekema, commented: Their New World Translation of the Bible is by no means an objective rendering of the sacred text into Modern English, but is a biased translation in which many of the peculiar teachings of the Watchtower Society are smuggled into the text of the Bible itself (The Four Major Cults, pp. 238, 239].
Dr. Ernest C. Colwell (University of Chicago): "A definite predicate nominative has the article when it follows the verb; it does not have the article when it precedes the verb; . . .this statement cannot be regarded as strange in the prologue of the gospel which reaches its climax in the confession of Thomas. `My Lord and my God.' " John 20:28
Dr. F. F. Bruce (University of Manchester, England): "Much is made by Arian amateur grammarians of the omission of the definite article with `God' in the phrase `And the Word was God'. Such an omission is common with nouns in a predicate construction. `a god' would be totally indefensible."
Dr. Paul L. Kaufman (Portland OR.): "The Jehovah's Witness people evidence an abysmal ignorance of the basic tenets of Greek grammar in their mistranslation of John 1:1."
Dr. Charles L. Feinberg (La Mirada CA.): "I can assure you that the rendering which the Jehovah's Witnesses give John 1:1 is not held by any reputable Greek scholar."
Dr. Robert Countess, who wrote a doctoral dissertation on the Greek text of the New World Translation, concluded that the The Christ of the New World Translation "has been sharply unsuccessful in keeping doctrinal considerations from influencing the actual translation .... It must be viewed as a radically biased piece of work. At some points it is actually dishonest. At others it is neither modern nor scholarly "78 No wonder British scholar H.H. Rowley asserted, "From beginning to end this volume is a shining example of how the Bible should not be translated."79 Indeed, Rowley said, this translation is "an insult to the Word of God."
Dr. Harry A. Sturz: (Dr. Sturz is Chairman of the Language Department and Professor of Greek at Biola College) "Therefore, the NWT rendering: "the Word was a god" is not a "literal" but an ungrammatical and tendential translation. A literal translation in English can be nothing other than: "the word was God." THE BIBLE COLLECTOR July - December, 1971 p. 12
Dr. J. Johnson of California State University, Long Beach. When asked to comment on the Greek, said, "No justification whatsoever for translating theos en ho logos as 'the Word was a god'. There is no syntactical parallel to Acts 23:6 where there is a statement in indirect discourse. Jn.1:1 is direct.. I am neither a Christian nor a Trinitarian.