I believe this is the first time you've brought up the word substance. Before you used being. If each is fully God, then it is 1+1+1. And, yes, it is polytheism even though Christians deny it vehemently. Three, fully God, individuals, cannot be one no matter how many millions claim it is.
Using math to try and disprove the Trinity is silly. It's what the Bible says that matters. Besides, 1 x 1 x 1 = 1. The doctrine of the Trinity is monotheistic, that is rather the point.
"Now if Christians said both that (1a) there exists precisely one God, and that (1b) it is not the case there exists precisely one God, they would contradict themselves. So also if they said both that (2a) there are three divine persons, and that (2b) it is not the case that there are three divine persons, they would also contradict themselves. But Christians do not affirm both 1a and 1b. Neither do they affirm both 2a and 2b. Rather, they affirm 1a and 2a. And this would be contradictory only if either 1a entails 2b or 2a entails 1b.
To put the point differently, when Christians say that God is both one and three, they do not say that He is one in the same way in which He is three. So, for instance, they do not say both that (1a) there exists precisely one God, and that (1c) there exist three gods. Nor do they say both that (2a) there are three divine persons, and that (2c) there exists only one divine person.
Since 1c entails 1b, affirming both it and 1a would be contradictory. And since 2c entails 2b, affirming both it and 2a would also be contradictory. But, as a matter of fact, Christians deny both 1c and 2c. In affirming 1a and 2a, then, Christians affirm that in one way GOd is one and in another way He is three. And in so doing they do not contradict themselves." (Douglas K. Blount)
Yes, and being and person are synonyms. They are interchangeable.
If you want to debate the Trinity as trinitarians understand it, then you must accept that the two words are used to refer to different things. They are being used to differentiate substance from personhood or centers of self-consciousness.
A lot of people get fooled by the three persons in one being.
That is what the Bible clearly reveals.
That Jesus is God is not at issue. That's a Red Herring.
It is very much an issue, for you. You believe Jesus is God, yet not the Father, which is good, but you also believe they are separate Gods. That makes you a polytheist, which contradicts Scripture:
Deu 6:4 "Hear, O Israel: The LORD our God, the LORD is one.
Isa 43:10 "You are my witnesses," declares the LORD, "and my servant whom I have chosen, that you may know and believe me and understand that I am he.
Before me no god was formed, nor shall there be any after me.
Isa 43:11 I, I am the LORD, and besides me there is no savior.
Isa 44:6 Thus says the LORD, the King of Israel and his Redeemer, the LORD of hosts: "
I am the first and I am the last; besides me there is no god.
Isa 44:8 Fear not, nor be afraid; have I not told you from of old and declared it? And you are my witnesses!
Is there a God besides me? There is no Rock; I know not any."
Isa 45:5 I am the LORD, and
there is no other, besides me there is no God; I equip you, though you do not know me,
Isa 45:6 that people may know, from the rising of the sun and from the west, that there is none besides me;
I am the LORD, and there is no other.
Isa 45:18 For thus says the LORD, who created the heavens (he is God!), who formed the earth and made it (he established it; he did not create it empty, he formed it to be inhabited!): "
I am the LORD, and there is no other.
Isa 45:21 Declare and present your case; let them take counsel together! Who told this long ago? Who declared it of old? Was it not I, the LORD?
And there is no other god besides me, a righteous God and a Savior; there is none besides me.
Isa 45:22 "Turn to me and be saved, all the ends of the earth! For
I am God, and there is no other.
Isa 46:9 remember the former things of old;
for I am God, and there is no other; I am God, and there is none like me,
(All ESV)
So, you really only have three options: 1) Jesus is not God, 2) God appears in three modes of being, or 3) a God that is at least a "binity."
That the three are one being is the issue. No one believed that until around 500AD.
Firstly, that there was, is, and only ever will be one God has been known for much longer than Christianity has been around, as I pointed out previously. That is one foundation of the Trinity. Secondly, you may not know early church writings as well as you think.
Clement states that the hope of believers is found in all three: "For as God liveth, and the Lord Jesus Christ liveth, and the Holy Spirit, who are the faith and the hope of the elect."
Ignatius often speaks of Jesus and the Son as being God: "Jesus Christ, our God" (Ephesians 1); "For our God, Jesus Christ, was, according to the appointment of God, conceived in the womb by Mary, of the seed of David, but by the Holy Ghost" (Ephesians 18); "God Himself being manifested in human form for the renewal of eternal life (Ephesians 19); "the Church which is beloved and enlightened by the will of Him that willeth all things which are according to the love of Jesus Christ our God . . . in Jesus Christ our God" (Romans 1); "For our God, Jesus Christ" (Romans 3); "Look for Him who is above all time, eternal and invisible, yet who became visible for our sakes; impalpable and impassible, yet who became passible on our account; and who in every kind of way suffered for our sakes" (Polycarp 3). He also has some very trinitarian language, "as being stones of the temple of the Father, prepared for the building of God the Father, and drawn up on high by the instrument of Jesus Christ, which is the cross, making use of the Holy Spirit as a rope" (Ephesians 9).
There is also the Nicene Creed, which I've mentioned already.
All this to say, although there appears to be no formally developed doctrine of the Trinity, all the foundations are there in various early church writings: 1) There is only one God (monotheism); 2) There are three divine persons; 3) The three divine persons are coequal and coeternal.
"Let us make man in Our image" is in the very beginning of the Bible. People were reading that passage for about 4000 years and didn't think it meant a Trinity. Then suddenly in the 5th century it means a Trinity? Not likely.
Again, it doesn't matter whether or not they saw it as referring to a Trinity; that doesn't determine the truth of the matter.
Gen 1:26 Then God said, “Let
us make man
in our image, after
our likeness. And let them have dominion over the fish of the sea and over the birds of the heavens and over the livestock and over all the earth and over every creeping thing that creeps on the earth.”
Gen 1:27 So God created man
in his own image,
in the image of God he created him; male and female
he created them. (ESV)
Notice the use of the plural in verse 26 and then the singular in verse 27 to speak of humans being created in the image and likeness of God. How do you make sense of it?
I didn't say I disagree. I wanted you to show how it contradicts Scripture. I was looking for you show it from Scripture.
It should go without saying. Polytheism is against Scripture and what Christians have always believed. Regardless, I have shown this above.