Biblical Unitarian: Rambam
Rambam, or Maimonides, was a Jewish philosopher and educator, and fierce defender of Jewish doctrines. Rambam did not write extensively on the Trinity since this was not a subject in Judaism, but he did have a few things to say about it in his letter on the resurrection:
“It is not rare that a person aims to expound the intent of some conclusions clearly and explicitly, makes an effort to reject doubts and eliminate far-fetched interpretations, and yet the unbalanced will draw the reverse judgment of the conclusion he sought to clarify. Some such thing occured even to one of God’s declarations. When the chief of the prophets wished by order of God to teach us that He is One, without associates, and to remove from our hearts those wrong doctrines that the Dualists propound, he proclaimed this fundamental: The Lord is our God, the Lord alone [Deut. 6:4]. But the Christians utilized this verse to prove that God is one of three, teaching that Lord, our God, the Lord makes three names, all followed by one, which indicates that they are three and that the three are one. Far be God from what they say in their ignorance. If this is what happened to God’s proclamation, it is much more likely and to be expected to happen to statements by humans.”
Rambam resented the fact Christians were “finding” the Trinity in places that made no grammatical sense. For this reason, Rambam replaced the word “echad,” meaning “one,” with “yachid,” meaning “alone”; thus, his translation “The Lord is our God, the Lord alone” (most translate as “the Lord is One“). His hope was to clearly convey the true meaning of the text, and not impose some esoteric message that is simply not in the text.
The source used can be purchased here:
Epistles of Maimonides: Crisis and Leadership