Jefferson promotes Unitarianism, which he virtually equates with monotheism: “I rejoice that…the genuine doctrine of one only God is reviving, and I trust that there is not a young man now living in the United States who will not die an Unitarian” (To Benjamin Waterhouse, June 26, 1822; his emphasis). According to Jefferson, adherence to the Trinity is tantamount to a belief that “there are three Gods” (ibid). As such, Trinitarianism does not qualify as monotheism; indeed, he calls it tritheism.
Jefferson traces this “tritheism” back to a mistranslation of the first verses of the Gospel of John, where, as he tells Adams, Jesus’ “doctrine of the Cosmogony of the world is very clearly laid down” (April 11, 1823). He quotes the verses in Greek: en arche en o logos, kai o logos en pros ton Theon kai Theos en o logos. Autos en en arche pros ton Theon. Panta de auto egeneto, kai choris auto egeneto ode en, o gegonen.
Which truly translated means ‘in the beginning God existed, and reason (or mind) was with God, and that mind was God. This was in the beginning with God. All things were created by it, and without it was made not one thing which was made.’ Yet this text, so plainly declaring the doctrine of Jesus that the world was created by the supreme, intelligent being, has been perverted by modern Christians to build up a second person of their tritheism by a mistranslation of the word logos. One of it’s [sic] legitimate meanings indeed was ‘a word.’ But, in that sense, it makes an unmeaning jargon: while the other meaning…explains rationally the eternal preexistence of God, and his creation of the world. Knowing how incomprehensible it was that ‘a word’… could create a world, they undertake to make of this articulation a second preexisting being, and ascribe to him, and not to God, the creation of the universe. The Atheist here plumes himself on the uselessness of such a God, and the simpler hypothesis of a self-existent universe (ibid.).
By rendering logos as “reason (or mind),” he undermines the notion of revelation through Scripture along with the belief that Jesus is the Word incarnate. As we will see, Jefferson holds that it is in nature, not in the Bible, that we should seek proof of God’s existence. For him, “mysteries” like the Trinity merely serve to promote schism and disunity. On the other hand, seeking God in nature offers the possibility of widespread agreement even among people of different faiths. This last point links Jefferson’s thinking about religion to the practical course he pursues on behalf of Unitarianism.