Christianity is based on the misunderstanding of what the Jews mean when we say: God is One.
Eliyahu HaNavi [Elijah the Prophet] teaches: Master of the Worlds, You are One, but not in a numerical sense.
Ein Sof has no number whatsoever. It is not One. It is not Zero. It is most certainly not three. Actually, the names of the numbers are Moral Teachings and the provide the conditions in the created world for Holy Interaction.
God created what Christians call the Holy Trinity together with the Creation. This means: First, Second, Third Persons, singular and plural were created in order to allow *interaction*. But God is most certainly not characterized by any number, not three and not one.
So what is One? What do we Jews mean when we say that God is One and that Israel is One?
The Hebrew word אחד, pronounced echad [guttural ch] is One. It is equal to the phrase האגד, which means The Unification.
The Name HaVaYaH is the unification of the Whole House of Israel, in all of in all of its Generations. I have provided the Hebrew proofs in the post directly below.
We are All One. ALL => EL.
אל אחד = 44 = אל האגד = יהיו האגד = האגד זוג באהבה = יו”ד ה”א ו”ו ה”א
By “collapsing” the Child of God into one figure, one personality who lived at one time [one in the simplistic sense] the fact that the entirety of the Jewish People who walk in God’s Moral and Holy Ways, are the Mashiach was quite intentionally blurred. By focussing on the emotionally-charged figure narratives, and physical representations, you could not see that the Jews who walk in the ways of Torah morally are God incarnate.