Source: The Trinity — Evidence and Issues, Robert Morey, Chapter 4, pp. 60-61
If we begin with the doctrine of the Trinity as the theological given, what kinds of things should we expect to find in the Bible? In other words, if A is true, then we will expect to find B, C, D, E, F, etc., true as well. And, if we do find them to be true, then this will verify A.
The issue becomes quite simple. Is the doctrine of the Trinity verified by Scripture? The only way to find out is to open the Bible and to examine specific texts to see what the authors of the Bible believed and taught.
Lets briefly outline some of the things which Trinitarians expect to find in the Bible.
But what if we do not find what we expect to find? Or worse, what if we find the direct opposite of what we expect to find? Since the denial of the consequence is always valid in logic, the doctrine of the Trinity could not survive under those circumstances.
For example, the doctrine of the incomprehensibility of God is a necessary corollary truth to the doctrine of the Trinity. While the former can be true without the Trinity being true, the Trinity cannot be true without the former being true. This is why anti-Trinitarians always attack this doctrine. If they can refute it, it would pull the rug right out from under the doctrine of the Trinity.
What if we found the Bible saying that God was perfectly comprehensible and could be understood and explained by human reason? This would at once overthrow the doctrine of the incomprehensibility of God without which the doctrine of the Trinity cannot survive.
But refutation is not just denial. (Dismissing something is not the same as refuting it. Declaring something to be true is not the same as proving something to be true.) Anti-Trinitarians must demonstrate in a positive sense that the Bible teaches the complete comprehensibility of God. They cannot simply deny the incomprehensibility of God and naively assume they have proven their own belief.
As we shall see, the failure to document their own beliefs is the main flaw in anti-Trinitarianism. They spend most of their time denying and ridiculing the Trinity and very little time demonstrating their own beliefs. Most of them function on the fallacy that, if they can “refute” the Trinity, they have automatically established their own beliefs. But, just because you have refuted someone else’s ideas does not mean that your ideas are right. You, too, could be wrong! This is one of the fundamental laws of logic.