It is possible to explain the Catholic-Catechism-loyal Trinity in a way that isn't impossible nor self-contradictory to the banned heresies by the RCC historically.

I have only 26 mins left to post and am unsure how to build the case since my opponent may make me waste all the effort if next effort is also low from him.

The main thing to realise is this.

The Catechism states all 3 of the Trinity are coeternal, coequal of 1 mind and never disagree nor change (in fact it says they never change their mind which makes praying for something extremely pointless if that's true).

The reality is that if all 3 are co-eternal, they began at the same point in time (but it denies they have any beginning or origin). While this can be true indeed, this would need to be true if all 3 were parts of the overall formation that modern Christians dub God (as a whole) or specifically old Jews dub Lord YHWH/YHVH. This entity would need to have always had these 3 parts in order for them to be coeternal and all we need for co-equal to work is some concept of them being a third of the God each.

This is completely banned as partialism heresy.

The Catechism summarizes the Trinity in this way:

We do not confess three Gods but one God in three persons, the “consubstantial Trinity.” The divine persons do not share the one divinity among themselves but each of them is God whole and entire. . . . In the words of the Fourth Lateran Council (1215), “each of the persons is that supreme reality, viz., the divine substance, essence or nature” (253).

https://www.catholic.com/magazine/online-edition/how-not-to-share-the-trinity

As for the overall Trinity the Catechism is also very confusing, it keeps reiterating that it is a mystery and has never been revealed to us by God, yet then why are we necessitated to believe it as if God revealed it to us?

Even worse when explaining Trinity they sometimes cite Paul and twist it to sound like Latter-Day-Saint theology where we end up becoming gods equal to Lord Jesus:

To achieve this destiny, we must be reborn and “conformed to the image” of God’s begotten Son. God accomplishes this rebirth in baptism by giving us his Holy Spirit, the third Person of the Trinity, whom Jesus also revealed.

“All who are led by the Spirit of God” are God’s “sons and daughters,” St. Paul says. When we address him as “Father!” it is “that very Spirit bearing witness with our spirit that we are children of God, and if children, then heirs, heirs of God and joint heirs with Christ.”

https://bccatholic.ca/voices/fr-vincent-hawkswell-bccath/the-trinity-the-central-mystery-of-our-faith

So, we are left with a big dilemma. How is it that we have 3 persons of God, it is monotheism not polytheism or henotheism and yet it is also the case all 3 are co-eternal, uncreated and co-equal while also not being 3 parts of God?

It leaves 1 key possibility... What if God has changed. Modalism.

There are 2 major issues with Modalism, firstly it means God hoaxed when he did things like say 'not your will but mine be done' and acted like he was worshipping the Father while on Earth as Jesus (since he was merely self-serving and gaslighting us then). The second issue other than God lying is that God can't be changing like that as per Catechism and Bible alike. God cannot be transforming from Father to Son to Holy Spirit as this defies his unchanging nature in at least the Father person. Then there is another issue that may not be major. How can Father cease and Son cease without in some sense having died off to become the next one?

the Modalism analogy is vapour, water, ice. The Partialism analogy is something akin to the heat, light and chemical energies of the Sun (which ironically is akin to what Orthodox do when describing it, 3 energies would be 3 parts of an overall energy-expressing deity with 3 expressions).

No matter what we circle back to a dilemma.

If all 3 are equally old (co-eternal) and equally valuable (co-equal) the only way this works is 3 parts of a codependent formation that is God, from the very start. Otherwise they either have 1 older that then begot the other 2 later on which still seems like 3 parts just 1 part begot the other 2 or we have the 3 persons being faked and a modalist heresy.

There are other heresies I can bring up, however, I need to wait for my opponent to defend with those heresies in his arguments to expose that he contradict the Catholic Church on this.

I will say G-d intervened here and prevented me posting the argument I made.

So Ill present it differently.

Ill use G-d to avoid using the L-rd's title in vain here.

Modalism dilemma

if the 3 persons are not parts of G-d and also not 3 G-ds it implies that it is 1 G-d switching between the 3. This is a severe Heresy to Catholicism as it denies true personhiod of the 3 and renders G-d a deceiver/liar.

3 G-ds cant be true; monotheism

Partialism dilemma

the 3 Persons being parts of the 1 G-d is a banned heresy.

Arianism dilemma

if F-ther making S-n occured, it means they are not co-equal and co-eternal or at least not 1 of them. Same goes for HS then, it would not be 3 co-equal co-eternal Persons of God especially as Flioque of Catholicism states HS proceeds from both Father and Son.

the Proceeding and Begetting dilemma

since Partialism and Modalism are both banned, there is no way for the begetting of S-n AND ALSO procession of HS from both to add up to be co-eternal clearly this axiomatically means F-ther existed before them in time and then made the other 2.

The Church (which when you say you specifically mean the Roman Catholic Church) has a Trinity that refutes itself existing due to Heresies they ban.

FORFEITED