Is it true that Jews during Jesus' lifetime were binitarian, that is believing that God was one being in two persons similar to how Christians have historically believed and taught that God is trinitarian having the persons of Father, Son, and Holy Spirit?
From "Two Powers in Heaven" by Alan Segal".
Though it was difficult to date the rabbinic traditions accurately in many cases, the results showed that the earliest heretics believed in two complementary powers in heaven while only later could heretics be shown to believe in two opposing powers in heaven. The extra-rabbinic evidence allowed the conclusion that the traditions were earlier than the first century. Furthermore, in comparing the literature, it was possible to define a number of dangerous scriptural interpretations central to the heresy and show how the rabbis countered them by bringing in other scriptures which unambiguously stated God’s unity. From this evidence it became clear that the basic heresy involved interpreting scripture to say that a principal angelic or hypostatic manifestation in heaven was equivalent to God.
Hopefully this will remove the downvotes.
Edit This might also help.
Then the Lord rained on Sodom and Gomorrah brimstone and fire from the Lord out of heaven, - Genesis 19:24
I'm told the clear reading is that there are two YHWH's but I only know a little Greek and no Hebrew.