One of the hardest things for Jewish people to deal with when it comes to Yeshua is the idea that he could be God in human form. The trinity just sounds like straight up polytheistic idol worship to Jewish ears.
Monotheism was the defining difference between the faith of Abraham and all the pagan worshipers surrounding him in the Mesopotamian basin. Every Jewish person knows that their God is one, and squirms inside when they see a church cluttered with images that seem like idols – the holy child in the arms of Mary, Yeshua on the cross… it might be like a believer going into a place of worship with star signs of the Zodiac all over the walls.
Jewish resistance to the trinity comes from the knowledge that the God of Israel is a jealous God, and that they must never bow the knee to any other. So how can we be so sure that the appearance of Yeshua and teaching of the trinity does not contradict the Torah’s insistence that only God should be worshiped? 

Does explaining the trinity tie you in knots?

An English preacher called David Pawson rightly noticed that we often feel awkward and embarrassed about the inexplicable trinity. How can God be three and one at the same time? “We don’t know!” We have to admit. There are metaphors of clover leaves having three parts to the one leaf… of water, ice and steam all being H2O… of the ability to be a mother, daughter and wife simultaneously, but none of these analogies really do justice to the mysterious Godhead we claim to know and love.

But, insists Pawson, the trinity is one of the greatest truths we have to share, because we alone, of all faiths, can declare the truth that God IS love!

In order to love, we need an object of affection, but since God is Father, Son and Spirit, he was already living in loving unity long before he created the world! In himself, God’s very essence is love with no need of outside intervention.
We could say that a singular God could be loving in nature, but to say that he IS love is a unique privilege of those who believe that he can give and receive love in and of himself.

They’re all there, the entire time, all through the Jewish Scriptures

The word “trinity” cannot be found in the Bible, but the truth is that the three of them have been there together all the way along.
Genesis tells us that God created the heavens and the earth by his word. John 1 tells us that the Word is Yeshua – that he was with God and was God from the get go, right there at creation. We also see the third person of the trinity, the Holy Spirit, hovering over the waters in the second verse of the Bible. Not sure about this? The first words of the Bible in Hebrew are  בראשית ברא אלוהים – In the beginning, God created (or “in the beginning, created God…”, because that’s the way Hebrew sentences are structured). The word for God is Elohim. This word Elohim, very interestingly, is plural. Still not convinced? The decision to create humanity is made. “Let us make man in our image, after our likeness”, says the plural God, in plural.
Later on we see hints of Yeshua appearing as “The Angel of the Lord”, which could simply be one of God’s many angels, except that those who encounter this one a) identify him as The Lord himself, and b) worship him.

There is no way that an angel of God – even a top level angel – would accept worship that belongs to God alone.

If you want to see what I mean, see what happens when “The Angel of the Lord” turns up to visit Hagar in Genesis 16 and 21, Abraham in chapter 18, and the One who stops him killing Isaac in 22:11, look at the interaction between Samson’s parents and the Angel of the Lord in Judges 13, and consider who the fourth person was in the fiery furnace that Daniel’s three friends were rescued from. As you ponder the texts and the dialogues, look carefully at the way people address this angel, at the way he refers to himself, and you will see that there is something divine going on here.
This angel speaks as if he is God, and people speak as if they have encountered God.
Because he is. And they have.
We also learn of the third person, the Holy Spirit, very much active in his own right in the Tenach – falling upon and anointing people with power to prophesy and act to accomplish God’s will. He empowers the artisans who make the tabernacle, falls upon Saul in 1 Samuel 10, and is spoken of by David in the Psalms and the prophets (“The Spirit of the sovereign Lord is upon me, for he has anointed me…” Isaiah 61). He appears many times throughout the scriptures, helping and enabling people to do the will of God.
We even see all three of them together in this verse:

“Come ye near unto Me, hear ye this:
From the beginning I have not spoken in secret;
from the time that it was, there am I;
and now the Lord GOD has sent me, and His Spirit.”
(Isaiah 48:16)

There they all are – all three of them together. The Lord God (Father), the One who he sent, who was with him from the beginning (Yeshua) and His Holy Spirit. In the Old Testament.
God repeatedly promises that he would come and live among them, in words that bewilder the mind if you are not ready to accept the deity of Yeshua. He says,

“Sing and rejoice, O daughter of Zion, for behold, I come and I will dwell in your midst, declares the Lord.
And many nations shall join themselves to the Lord in that day, and shall be my people.
And I will dwell in your midst, and you shall know that the Lord of hosts has sent me to you.” (Zechariah 2:10-11)

Yes, it was always God’s intention to come and live among us as Yeshua. And you can see the sameness yet separateness in these verses – he speaks as God himself, yet tells us that the Lord of Hosts has sent him.
We also see the God’s Son mentioned several times in the Tenach (Jewish Scriptures):

Psalm 2:2 –
Kiss the Son, lest he be angry, and you perish in the way, for his wrath is quickly kindled.

Blessed are all who take refuge in him.

Proverbs 30:4 –
Who has ascended to heaven and come down?
Who has gathered the wind in his fists?
Who has wrapped up the waters in a garment?
Who has established all the ends of the earth?
What is his name, and what is his son’s name?
Surely you know!

Daniel 7:13 –
and behold, with the clouds of heaven there came one like a son of man,

and he came to the Ancient of Days and was presented before him.

Incomprehensible, but true

So although this idea seems alien to most Jewish people (and frankly, rather bewildering to most believers) a careful study of the Scriptures shows us that Yeshua did not suddenly appear two thousand years ago. As he says of himself; “Before Abraham was, I AM” (John 8:58).

Show the world you are One for Israel!