Why Is God A Trinity? Unanswerable Question?

So a co-worker of mine has asked this question and I told him I’m not sure there is an answer to that question but that I would look into it.

I have The Compendium of Faith by St Thomas Aquinas published as Shorter Summa by Sophia Institute I started to read the chapter on the Holy Trinity before being asked this question and having gotten sidetracked need to get back to reading my book.

St Thomas Aquinas talks about how God is essentially the only perfectly fully formed person.

There is God’s self which is perfect and God’s perfect knowledge of His self, and lastly God’s perfect of love of both His self and His knowledge of His self.

I plan to for finish this chapter and would surmise to go to Augustine and Jerome next but does anyone know where and what I should read from those sources?

Lastly can the question be answered?

Do we know why God is a Trinity or is this a mystery only?

This went completely over my head.

I think we can be sure it was not a random act but has specific purpose to it. And I think it shows this in the reflection of the trinity in the human family. Jesus and his bride the church with the Holy Spirit inspiring the faithful reflects the trinity. The same with the domestic church as God is with the husband and the wife forming the trinity.

There is a very specific usage of this in these cases and ultimately, it reflects not only God’s love for us but also how humans are truly made in the image and likeness of God because we participate in the trinity of God in such a profound way.

Could there be other reasons we are unaware of and are thus a total mystery? Of course there are, and I bet there are. But we at least can see clear examples of why the trinity has been an important aspect in our theological understanding of God.

It went over mine too.

Father Self

Son Knowledge of Self

Holy Spirit love of both self and knowledge of self

Each are unique personalities of one person.

This is how is St Thomas Aquinas explains the Trinity instead of thinking of it as three Divine persons that make one godhead.


Here’s the thing I think there are plenty of good answers as to how God can be a Holy Trinity and how we can explain the three persons in one but the question my coworker is asking is why is God three-in-one.

Why is a much harder question than how.

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Is the coworker asking like “why did God chose three and not four or two?”

I think we can see examples of why three makes sense, such as these ones I noted. But perhaps we will never know for certain why God chose to do something.

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No I think it’s more like why is God three persons in one?

He may also be wondering why 3 and not 2 or 4 as you mentioned.

The thing is that God being three persons in one is not a matter of choice as it’s a matter of being since he’s the first mover.

It’s in most probability an unanswerable question for our feeble human intellect.

Essentially only God knows God fully and perfectly.

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Your friend’s why question is like Leibniz’s question asking why there is something rather than nothing.

This can be answered along the same lines as atheists (like Lawrence Krauss and Bertrand Russell) answer Leibniz.

It’s not a mystery. It’s not a dichotomy. It’s not a why question. It’s a how question.
Why is heat hot? This is not an unanswerable question. It’s a redundant question.


This is only my simple way of putting it, not anything official:
Father—because we needed a Creator, a Father who formed us in our mother’s womb. We can only see Him face to face in Heaven once purified

Son—God allowed Himself to take on human form like us so that we could relate. He did this to suffer and die for us and become Our Savior. Even though He went back to be with the Father,and He remains with always in the Eucharist.

Holy Spirit—Because God knew we needed a Paraclete, a Cou nselor the One to set us on fire with His love. One to give us wisdom and guidance.

ALL God in different person’s but all in One.

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It’s the only way we could experience Him and relate to Him. Was He only the,Father we wouldn’t know Him fully until Heaven. But He came down to us as one of us here and remains with us here. He walked on the same Earth that we walk on. Without His Holy Spirit His words would mean nothing to us. It takes His Holy Spirit for us to be able to understand the Almighty God.

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wouldn’t it be reversed…Son self, Father knowledge of self?

The way I understood it was that God is self and when God thinks of himself it’s his knowledge of self which is the perfect reflection of self since God knows himself.

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I guess God could have chose to do anything He wanted. He was not limited to be a Trinitarian form but chose to be such. Therefore, we can at the very least infer that there is a very specific reason why God is a trinitarian form

I would say it’s probably more accurate to say rather than God chose to be a trinity since God is in a eternal state of being without beginning or end but instead he chose to reveal himself as a trinity.

However the problem with this type of thinking is that God is perfect in his being and essence which is the same so if God is a trinity he has always been and is a trinity.

It’s possible that our understanding of the Holy Trinity is a bit flawed and mind you this is just St Thomas Aquinas understanding of how three can be one.

There are other theologians the saints that we can draw from.

interesting. that’s pretty cool. Your making me think about how we are created in the image of God with our Intellect, Will, and I guess physicality? (Father, Holy Spirit, Son respectively) Not really sure how to describe the material part?

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You can look at it this way God the Father is self that self looks into the mirror or in Aquinas’s definition his conscience mind and thinks of Himself and because God perfectly knows Himself he has perfect self-knowledge and when God sees Himself and simultaneously thinks of Himself he both loves Himself and the knowledge of Himself.

God is a perfect and fully formed Divine being who Himself is perfect whom perfectly knows Himself and whom perfectly loves Himself and is neither lonely or lacking.

Everything God ever created was already in being within Himself since He is the first mover.

God the Father is the self of God, God the Son is a knowledge of self and as we know Jesus is the logos the icon of God and the Holy Spirit is the love of God’s self and the knowledge of Himself and so the Holy Spirit is the love of God Whom guides us.

God didn’t send himself to earth, He sent His son who represents the Father.

The existence of the Trinity is something revealed to us. The how/why is not revealed and most likely we wouldn’t be able to understand it with our limited human mind.


What amazes me is that you could meditate on this stuff for many many years…and Thomas turns around at the end of his life and says all his work is but straw lol…WOW! God is great!

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When questioned by my 6 year old as to how God could have three persons, my wife explained that liquid water, water vapor, and ice all exist in different states, yet are all the same essence - water. It made sense to my daughter, so works for me. I don’t think complete understanding of God’s mysteries is as important as complete acceptance of them.

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