Why is the Trinity considered polytheistic in traditional Jewish thought? [closed]

Question

I've read a couple questions on this site and other Jewish sources stating the traditional Jewish view is the Christian concept of the Trinity is polytheistic. However, I haven't found any questions or other resources explaining why the Jews take this position.

Why do Jews interpret the Trinity in this way if the traditional Christian view is that the Trinity is monotheistic? For example, Aquinas goes to great lengths to explain how to make sense of three persons in a single, simple G-d, and Aquinas is considered one of, if not the, defining theologian for the Catholic church, which in turn is (I think?) the largest branch of Christianity throughout history.

https://www.newadvent.org/summa/1003.htm#article7

On the contrary, Augustine says (De Trin. iv, 6,7): "G-d is truly and absolutely simple."

https://www.newadvent.org/summa/1028.htm#article2

Thus it is manifest that relation really existing in G-d is really the same as His essence and only differs in its mode of intelligibility; as in relation is meant that regard to its opposite which is not expressed in the name of essence. Thus it is clear that in G-d relation and essence do not differ from each other, but are one and the same.

Were Jewish authors not aware of these theological developments, considered them to be erroneous, or some other reason? If erroneous, any idea where the error lies? Is the Christian concept of the Trinity just considered to be flat out logically impossible? E.g.

• square circles
• married bachelors
• sets of all sets that contain every set but themselves

If the Trinity is considered to be a logical impossibility, any pointers where I can find the proof/argument as such? Or is it thought to just be an obvious self contradiction, like the mathematical equation 1=3?

Thanks!

Answer 1

Let's stop and think for a moment: "Aquinas goes to great lengths" - if the trinity was pure monotheism, why would one have to go to great lengths to prove it was so? And this is consistent throughout the various Church Fathers that tried to explain the trinity. None have been able to explain it satisfactorily, but more importantly, the need to come up with different explanations already in itself shows that it is not purely monotheistic. Christians still struggle to explain it, both to themselves and to others.

Judaism has a couple of problems with the trinity:

a. The triune identity of god - this goes against various verses in the Bible that attest to God's oneness, such as: "And the LORD shall be king over all the earth; in that day there shall be one LORD with one name." (Zechariah 14:9), "Hear, O Israel! The LORD is our God, the LORD alone." (Devarim 6:4) and "I the LORD am your God who brought you out of the land of Egypt, the house of bondage. You shall have no other gods besides Me." (Shemot 20:3-4).

b. The physical manifestation/corporeality of god - this goes against verses that state that God is not physical, such as: "God is not man to be capricious, Or mortal to change His mind. Would He speak and not act, Promise and not fulfill?" (Bamidbar 23:19), "To whom, then, can you liken Me, To whom can I be compared? —says the Holy One." (Yesha'ayahu 40:25) and "For your own sake, therefore, be most careful—since you saw no shape when the LORD your God spoke to you at Horeb out of the fire." (Devarim 4:15)