Suppose that you lived in a two-dimensional universe. Your entire physical experience is based on length and width. There is no up, no going over or under. It is the world that a figure on a piece of paper experiences. Suppose one day a three dimensional monster steps on the surface, or more accurately the plane of existence, on this world. The inhabitants of the two dimensional world are terribly afraid. From their view two strange shapes suddenly appear on their planet. By walking around each they observe that the two shapes are similar, but not identical. Logically they conclude that these are two separate creatures of because they are not connected. Because of the unknown and possibly dangerous nature of these creatures the dwells of this two-dimensional world build a wall around each of the two creatures. They post guards and the rest go to sleep for the night. Next morning a section of the wall is removed. It is discovered that the two creatures are gone. Naturally this brings up some serious debate among them. Some argue that supernatural event have taken place because there is no explainable way the creatures could have escaped with out breaking down the wall and alerting the guards. Others counter that there must be a purely material solution to the problem and call the supernaturalists superstitious. The naturalist counter that a purely logical solution will eventually be found to the problem. From the point of view of the monster the escape was easy. During the night he walked out of what looked like lines drawn around his two feet, over the heads of the 2-D guards. If one views the happenings from the monsters perspective the answer becomes quite easy.
Switching gears a little bit I want you to imagine a three-dimensional cube. It has height, length, and width. Now pass that cube through the 2-D plane. As the inhabitants of this plane observe it traveling through it would appear to be a square. Try to explain to them that the square they saw contain six squares, yet was one object. They would think you were crazy.
Now transition to a 3-D world, like we live in. What might we see if a four-dimensional object (with all sides of equal lengths) passed through out world? We would see a cube. Theoretically it would also contain eight other cubes, yet be one solid object. There is no us to imagine such an object from the perspective of our native dimension. Your brain starts to sizzle and smoke if you do. A four dimensional being could appear in our world as separated three-dimensional beings yet still be one being. Start increasing the number of dimensions and the possibilities are beyond comprehension. It may sound like science fiction and some science fiction writers have explored the idea i.e. Flatland: A Romance of Many Dimensions, C.S. Lewis in the sense that follows. I think it may help us understand the Trinity.
The Trinity is not logical, at least to our finite minds. However, to beings from another perspective it might be perfectly rational that three coexisted persons can exist in one being. I think all aspects of Christianity are rational, but some are rational in away beyond our own reason, “super-rational.”
I do want to make it clear that I don’t believe that God is simply a being from the fourth or any other dimension. He is who He is. For certain people thinking about the Trinity this way doesn’t prove that it is true but removes barriers to belief. The Trinity is a doctrine of Christianity that causes people a lot of trouble. I write this to show that the Trinity is not so illogical as people accuse it of being. In a broader sense it is rational to believe in certain things that we are not able to logically comprehend. Of course other tests of truth should be applied.
If this helps you than good, if not you can ignore it.