Premise 1: God is not the author of confusion.
Premise 2: The Trinity is confusing.
Conclusion: God is not the author of the Trinity.
This is a very interesting argument made by some anti-Trinitarians, and because of the inclusion of a Biblically based concept (1 Corinthians 14:33), it effectively nullifies the incredulity fallacy that such arguments usually commit.
There are, however, two main problems with this argument. The first is that it fundamentally misunderstands 1 Corinthians 14:33. In fact, one might question whether this is even the correct translation. Not all translations render the word "confusion". "Disorder" is just as common. In fact, when I compared all translations on Bible Gateway, there is almost a 50/50 split between those that use "disorder" and those that use "confusion".
This makes perfect sense with the context of the verse. The verse alone contrasts "confusion" with "peace", which again fits nicely with the context of the verse. The whole passage (verses 26-40) speaks of the chaos in the Corinthian church, explaining how this is not the way God intended it. When the Corinthians met as a congregation, each of them had a psalm, a teaching, a tongue, a revelation, or an interpretation. When they would speak in tongues, they would do so simultaneously, and without an interpreter. When they received revelations, they would all speak over each other. The congregation was just a total mess. It wasn't a service, it was a verbal brawl! Hardly fitting for a gathering of God's people.
And so we see that 1 Corinthians 14:33 has nothing to do with how well we, as humans, can be expected to understand God. Indeed, if we could understand God, what kind of God would He be? He may as well be a man. Indeed, less than a man, for more often than not, we cannot understand each other, or even our very selves. As the prophet declares, "The heart is deceitful above all things, And desperately wicked; Who can know it?" (Jeremiah 17:9). Thus, if we cannot be expected to understand even our own selves, how can we fully grasp the God whose thoughts are higher than our thoughts, and whose ways are higher than our ways? (Isaiah 55:9). God may not be the author of confusion, but if you use this as an excuse to dismiss His tougher teachings, you may as well bin that Bible, because most of us would be lucky to so much as memorise a whole chapter.
But this brings us to the second problem with the initial argument. Nothing is more confusing than telling people the opposite of what you mean. If God didn't want us to believe in the Trinity, He would not have inspired the prophets and Apostles to write about the Trinity. And yet, scripture is so unbelievably littered with references to the Trinity, we would be hard pressed to collect them all. Even the Jews, prior to the birth of Christ, believed in a multipersonal God. Though their revelation was incomplete, they were able to glean from scripture that God is multipersonal, postulating that YHWH was made up of at least two co-equal persons.
Thus, the question anti-Trinitarians must answer is, if God is neither the author of confusion, nor is He a Trinity made up of the Father, Son and Holy Spirit, why does scripture so strongly point to the the Father being God, the Son being God, the Spirit being God, and all 3 being one God? It may well be confusing that God, who is greater than us, has an attribute we cannot fully comprehend, but in my eyes, it is far more confusing that God would tell His messengers a thing that is not true. Thus, if anything, the argument backfires against itself.