Do you ever get even a little tiny bit bothered by the fact that God did not ever reveal Himself as Trinity in the Old Testament & Jesus, although did say He & the Father were One & He is I AM, didn’t clearly reveal God as Trinity either and that the clear definition of Trinity wasn’t revealed in the Bible at all, but only became clear a few hundred years after Jesus’ Resurrection?
I believe in the Trinity, but every now & again I wonder.
How is it okay that for thousands of years God’s chosen had only been taught that God is ONE. And that the first Christians didn’t know about God being Trinity as we now know?
How have those of you who have ever been bothered by this come to reconcile this?
I think the only problem was with God the Son - Who was not incarnate yet. So naturally, the concept would not be present.
I respectfully differ in regards with the Spirit of God. Here’s a small sample of the Holy Spirit’s work in the OT (RSVCE):
*Ge 6:3 Then the Lord said, “My spirit shall not abide in man for ever, for he is flesh, but his days shall be a hundred and twenty years.”
Ge 41:38 And Pharaoh said to his servants, “Can we find such a man as this, in whom is the Spirit of God?” 39 So Pharaoh said to Joseph, “Since God has shown you all this, there is none so discreet and wise as you are; 40 you shall be over my house, and all my people shall order themselves as you command; only as regards the throne will I be greater than you.”
Nu 27:18 And the Lord said to Moses, “Take Joshua the son of Nun, a man in whom is the spirit, and lay your hand upon him; 19 cause him to stand before Eleazar the priest and all the congregation, and you shall commission him in their sight. 20 You shall invest him with some of your authority, that all the congregation of the people of Israel may obey.
Dt 34:9 And Joshua the son of Nun was full of the spirit of wisdom, for Moses had laid his hands upon him; so the people of Israel obeyed him, and did as the Lord had commanded Moses.
1 Sa 10:6 Then the spirit of the Lord will come mightily upon you, and you shall prophesy with them and be turned into another man.
1 Sa 10:10 When they came to Gibe-ah, behold, a band of prophets met him; and the spirit of God came mightily upon him, and he prophesied among them.
1 Sa 19:20 Then Saul sent messengers to take David; and when they saw the company of the prophets prophesying, and Samuel standing as head over them, the Spirit of God came upon the messengers of Saul, and they also prophesied.*
So the concept of the Spirit of God is pretty abundant in the OT.
Paul also explains the mystery of Christ and that it was kept hidden until His Incarnation and the Revelation of God to His Apostles:
Eph 3:1 For this reason I, Paul, a prisoner for Christ Jesus on behalf of you Gentiles— 2 assuming that you have heard of the stewardship of God’s grace that was given to me for you, 3 how the mystery was made known to me by revelation, as I have written briefly. 4 When you read this you can perceive my insight into the mystery of Christ, 5
which was not made known to the sons of men in other generations as it has now been revealed to his holy apostles and prophets by the Spirit; 6 that is, how the Gentiles are fellow heirs, members of the same body, and partakers of the promise in Christ Jesus through the gospel.
This same Spirit of God made it known to us.
The Jewish people had plenty of opportunities to hear Christ and the Apostles. They just did not agree with them

or with God’s revelation

So while the Trinity is indeed a divine mystery, the Jewish people did have the Spirit of God with them.
Peace.