This is an extensive topic that you have presented here. It would take many days and more to discuss it with some justice.
So here is one of your links and an area within it I believe confidently is incorrect. I will only give a BRIEF reason why it is incorrect because the full answer would be too extensive. This area spills over into what 95% of so-called Christians believe in..... ..it may derail your topic of discussion quite quickly with my chosen area of discussion.
From the
Historic Church Documents at Reformed.org you listed.
I disagree with question 25 part (b)..that there are three distinct persons that are the eternal God.
Brief answer: There is one God Almighty and eternal, one son of God born of God via his spirit. There is only God with his many roles including being a Father, his son, 100% human being on earth. The spirit is God, an extension and power into our world that communicated to his creation. The spirit is therefore not another personality of God, it is actually what he is composed of... if you let scripture be your guide.
I noticed an extensive scripture support the author of this Heidelberg Catechism gave for his answer. They are all incorrectly interpreted in the main. I can go through every one of them and provide you with where the author misinterpreted the scripture. I believe that would be an over-kill here.
Let me pick out a couple though:
The easy one is 1 John 5:7 -8 actually: “For there are three that bear record in heaven, the Father, the Word, and the Holy Ghost: and these three are one. And there are three that bear witness in earth, the Spirit, and the water, and the blood: and these three agree in one.” (KJV)
This version of 1 John 5:7-8 was not found in any Greek manuscript until the 11th century AD, although considered as the original version. Many scholars including Catholic, admit that verse 7 was a deliberate insertion t o support Trinitarianism. I also agree.
The original version was:
“For there are three that bear record/witness: the Spirit, and the water, and the blood: and these three agree in one.”
This scripture had everything to do with Christ's baptism and death until it was twisted in to a nonsense satement without any useful purpose. It seems the added words were trying to legitimize Jesus as the logos because there was insufficient support in scripture at that time?? Well frankly John 1:1-2 and 14 is not really any proof, right, without inserting some text in other areas to reinforce the incorrect interpretation of the 'word'? I would say yes. (For another discussion)
Oh yes Matthew 28:19 is also an easy pick:
“Therefore go and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit.” (NIV)
These words of the Trinity formula (Father and of the Son and of the Holy Spirit) were added in the first translation of the Bible from Greek into Latin in the 4th Century AD as a political decision in Rome.
St. Jerome or Eusebium considered the ‘Father of Church History’ wrote about this passage of scripture before it was formally first translated and handwritten into Latin. He did not have the Trinity formula in it.
He wrote “Go ye and make disciples of all the nations in my name.” (Book III of his History, Chapter 5, Section 2 and also in Oration in Praise of Emperor Constantine, Chapter 16, Section 8).
Now when we read of either the water or spirit baptism performed in other parts of scripture, we find that it reads like Eusebium’s version. How could the apostles and disciples get it so wrong that they always baptized in Jesus’ name only (Acts 2:38, 8:16, 10:48, 19:5). And why wouldn’t they just baptize just in Jesus’ name? Jesus was the perfect sacrifice and savior for mankind. It even makes logical sense. And why would the impersonal roles of God as the Father and Jesus as the son and God’s spirit be relevant in mimicking and having faith in what Jesus did at baptism and on the cross with his death. God did not die on the cross, the human called Jesus did. God’s spirit did not die on the cross either. Even if this portion of scripture of the Trinity formula was true which it is not, it still does not say these titles or roles formed one God. - meaning no support for a Triune God here.
You can see how Matthew 28:19 and 1 John 5:7-8 had added text to support the Trinity formual and concept.
There much more I can add with scripture support..