My answer is to answer the question and to provide some rebuttal to Ronald Kimmons in particular and the others here who claim the Trinity is irrational.
First, I will admit the concept of the Trinity is not common sense. However, that does not mean it is irrational. Einstein’s theories of relativity and the theories of quantum mechanics are not common sense either. But, we don’t deny them. They are rational and experimentally supportable. We cannot produce experiments to support the Trinity, but we can rationally see it as explanation for a conundrum that is clearly evident in the Bible. The standard statement to justify why the Trinity is not a contradiction (which is a different matter than whether it is rational to believe it is true or not, i.e., a statement can be logical, but what it states doesn’t have to exist) is that the Trinity consists of three whos and one what. The Trinity would indeed be a contradiction if it was three whos and one who at the same time. Rather, God is one essence in three persons. If we boiled “humanness” down to its essential essence, we could easily have a case of three persons, or even more than 7 billion persons, and one humanity. The Trinity is not quite that simple, but it demonstrates how the concept at least is not contradictory.
Ronald Kimmons made the point that many of the common analogies for the Trinity are actually heretical. He is 100% correct on that! He is also correct in that most Christians, including probably the majority of clergy, do not understand it. If the clergy don’t understand it, then in general the people taught by them won’t understand it either.
Now, Ronald himself starts being a little misleading (unintentionally, I’m sure) in asking the reader to draw a triangular circle. He says you can’t because it is impossible to conceptualize. Actually, it isn’t because of a person’s ability to conceptualize that is the problem, but that a triangle and a circle are different by definition. A triangular circle IS a contradiction of terms. However, as already stated, the Trinity is NOT a contradiction of terms. It IS difficult to conceptualize, though. But, I wouldn’t say it is impossible. If it truly exists, then in some manner it can either be conceptualized or we just have to admit we have no experience by which to compare it to or to describe it with given our limited language. Quantum physics was beyond our experience at first. But in nearly a century of study, it is being understood better and better such that we can devise transistors, lasers, and even quantum computers. Exactly what is going on in that world is difficult for us to perfectly understand because any attempt to observe it influences the result. But, we can at least describe it in a useful way. The Trinity is no different except that all the observations have to come from the Bible.
Ronald says that he can’t believe in a substance that was at once wholly milk and wholly wine at the same time – but not a mixture of the two, because it doesn’t make any sense. He is absolutely correct! The reason is that milk and wine are both substances. It is a contradiction again to say something is made of up two substances but isn’t a mix of two substances. We must be careful, including myself, to not argue against something, or even for something, with bad logic!
In bold Ronald says, “Christ told us that we are saved by knowing God, and Trinitarianism gives us a God who cannot be known on even the most fundamental level.” I would say that it is through the Trinity that we come to know that God. Not that we need to understand the Trinity concept – I don’t think that is actually a requirement for salvation – but we need to acknowledge that God has revealed Himself through the Trinity. By acknowledging that, we are acknowledging the works of God. He brings salvation to us through His works. Keep in mind the earliest Christians did not know the term “Trinity”, but they did know of the Trinity and how God has made Himself known.
Now, let us think more about what the Trinity is. I think the traditional concept of the Trinity is correct and is supported by Scripture. To do a proper job to show this, I could teach a whole college seminar. So, what I provide here is just a start. But hopefully it is enough of a start to help settle the matter.
Isaiah, chapters 42 through 44 provide a lot of words from the LORD God to the prophet about him alone having created the universe and being the source of life for all people. In 44:6, Isaiah says, “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.” He is the one who blots out transgressions. In 43:11, it says, “I, I am the LORD, and besides me there is no savior.” So, we can say that the LORD God is adamant that he is it and that all glory for his achievements only go to him! Without listing all references here, we can also note that particularly in Isaiah, but throughout the Bible, there is mention of one who is sent by the LORD God to redeem the people called the Messiah. Many times it is a bit confusing whether the reference it talking about the LORD God, or about the Messiah. This Messiah is mentioned in Isaiah 53, which nearly everyone can identify as Jesus. Daniel 7:13-14 tells of “one like a son of man”, who came before the Ancient of Days. To this one, “was given dominion and glory and a kingdom, that all peoples, nations, and languages should serve him; his dominion is an everlasting dominion, which shall not pass away, and his kingdom one that shall not be destroyed.” This resembles Matthew 28:18-20, where Jesus says, “all authority in heaven and on earth has been given to me. Go therefore and make disciples of all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Spirit, …” Why in the “name of” rather than in the “names of”. If God does not share his glory and should get full credit for the salvation of the world, as stated in Isaiah, then how can this one like a son of man receive all of it for himself? No one is to be worshiped except for God. That is a major tenet of Judaism! Yet this son of man is being worshiped. In Revelation 6 the Lamb of God is worshiped, which also has parallels to the Daniel passage. In Revelation 1:8, it says, “I am the alpha and the omega, says the LORD God, who is and who was and who is to come, the almighty.” Yet, in verse 12, one like “a son of man” appears. Verses 17 and 18 follow, “he laid his right hand on me, saying, Fear not, I am the first and the last, and the living one. I died, and behold I am alive forevermore, and I have the keys of Death and Hades.” Lastly, at the very end of Revelation, in chapter 22, verse 12 says, “Behold, I am coming soon, bring my recompense with me, to repay everyone for what he has done. I am the alpha and the omega, the first and the last, the beginning and the end. … (v16) I, Jesus, have sent my angel to testify to you about these things.” It is clear that the divine nature of Jesus and God are one and the same. Yet, Jesus prayed to his father and the spirit descended upon him. So, they are different persons. (I have not said much about the Spirit here, but much more could be referred to to show the Spirit is also the same as God.)
The beginning of the Bible begins with God creating the heavens and the earth. His spirit is brooding over the face of the formless creation. He spoke, and things came to be. Colossians 1 says much about Jesus being the image of the invisible God and a participant in creation. He is also the one reconciling all people to God. How can a mere man bring about peace between man and God, especially when God says it is his to do?
Now to draw the picture! The earliest church fathers had spoke of the incarnate word that came from the Father. They also speak of the Spirit of God as being like a breath. When Jesus breathed on his disciples after his resurrection, he told them to receive the Holy Spirit. In John 1, it says that the Word was before the face of God, and that God was the Word. The word became flesh. Jesus was the embodiment of all righteousness, all that encompasses the character of God. Many times when the New Testament says God, it is speaking of the Father, as if the Father has the stand alone title of God. Those who have the Holy Spirit have the mind of God within them. The Holy Spirit conveyed the words of the Father (of God), to the prophets. The Holy Spirit illuminates the mind of the believer to understand the words written. The Holy Spirit came over Mary when she conceived of Jesus. Now consider this: a lens brings closer in an image what we can’t see well on the other side. Jesus said in John 14 that if you have seen me you have seen the Father. Jesus is like a lens, projecting the fullness of the infinite and eternal Father, into time and space for all his disciples to see, hear, and touch. Jesus is 100% a physical man with 100% the divine nature of God. That is not a contradiction, since they are different types of “substances”, physical and spirit. Pulling this all together, we can have a picture of God, who is the Father, speaking his words, which are transmitted on his breath. We receive the words of God from the Spirit which proceeds from the Father. The Spirit brings those words to us. Jesus is the embodiment of the Word. God’s words have the same character as himself. They have an eternal nature that exists in the mind of God from eternity. The Spirit is the means by which the words come from the Father to us. The only thing missing in all of this is the personal nature of the Word and of the Spirit. Yet, the Bible is full of references to each having their own will, thoughts, and etc in addition to that of the Father.
This is still not easy to comprehend fully. But it is rational. I think many think of “God” as a distinct being and that the Trinity represents three other beings. Whereas, “God” is the Father and the divine nature of the great “I am”, the “first and the last”, the “alpha and the omega”. The Word and the Spirit are beings that have eternally proceeded from the Father with exactly the same divine nature as the Father, and of one purpose. Since they are eternal, there never was a time when they did not also exist. They are not created beings because their nature is eternal, having always existed. To me, the only thing about this that is confusing and difficult, is how the Son of God and the Spirit of God can be eternal yet proceed from the Father. Eternity is beyond our comprehension. But that doesn’t make it irrational. This is where our experience makes it difficult. But, not irrational.