I found the following from 1996 -- Paul Sigmund, of Princeton, reviewing John Marshall, of Johns Hopkins on John Locke. The significance of the review is both Sigmund and Marshall are preeminent Locke scholars. I have had the good fortune to meet and chat with Dr. Sigmund. What I am going to reproduce from the review is what I discussed with him. Locke's Christology means nothing to the overwhelming majority of folks. So when I asked Dr. Sigmund whether he thought Locke believed in the Arian or Socinian heresies, he seemed genuinely happy to meet another relatively rare fellow traveler who takes an interest in such matters.
With that, here is the passage:
For theologians, the most interesting parts of the book are those that examine Locke's beliefs on original sin, the atonement, and the divinity of Christ. Locke always claimed to be a member of the Church of England. He believed that the Scriptures were divinely inspired, wrote a commentary on the Pauline epistles, and received the sacrament at his residence when he could no longer attend church services. Yet as early as 1680 he wrote in his journal that a just God could not condemn men for sins they had not committed, and he repeatedly questioned the doctrine of original sin. Locke believed that Christ died not to atone for Adam's sin, but to show us the way to eternal life. In turn, this undermined one of the arguments for the divinity of Christ, that an infinite satisfaction was required to atone for an offense to an infinite being. Locke never explicitly denied Christ's divinity, but M. assembles evidence, such as Locke's commentaries on the opening of the Gospel of John, which seem to amount to such a denial. Locke insisted he was not a "Socinian," i.e. Unitarian, but associated with Unitarians and read many Socinian books. He was sympathetic with the latitudinarian wing of Anglicanism but, according to M., parted company with them on the question of the Trinity.