Is the Doctrine of the Trinity Reasonable?

The doctrine of the Trinity is at the heart of orthodox Christian belief, and seeks to explain the relationship between the Father, the Son Jesus and the Holy Spirit. The equal nature of the Father and Jesus was affirmed by the Council of Nicaea in AD325 in dealing with the Arian heresy (and expressed in the Nicene Creed). The equal nature (or consubstantiality as it is technically known) of the Holy Spirit also was added into an expanded creed at the First Council of Constantinople in AD381.

The doctrine is perhaps most simply expressed by the formula "The Father is not the Son. The Son is not the Spirit. The Spirit is not the Father. The Father is God. The Son is God. The Spirit is God."

Non-believers have often poured scorn on a doctrine which is so difficult to grasp, and which is not explicitly contained in Scripture, but the doctrine is an attempt to bring together and formalise the teaching of numerous separate parts of Scripture. I contend that, regardless of theology, such a doctrine is reasonable from purely (a-theistic) physical considerations. My argument is as follows:

Consider a two-dimensional world inhabited by sentient beings whom, for want of a better term, I will term 'flatties'. In fact it is not possibly to imagine what flatties would see, since it would be an infinitely thin horizon, so we will allow it a nominal depth. A flattie sees other flatties as horizontal bars, their length decreasing the further distant they are. When two flatties pass, one is seen to disappear behind the other. Such is the simple visual experience of a flattie.

Now suppose you burst into their world with three fingers of your right hand. The flatties would see three beings as flesh-coloured bars (distinguishable from each other with care) like themselves, which could pass behind or in front of each other and of any flatties they interacted with. But as you 'lift' your fingers out of their world and put them down again, they would see these finger beings suddenly disappear and reappear elsewhere. The flatties would experience the finger-beings as completely separate, but not completely independent of each other, as they never appear at a great distance from each other. Moreover when a flattie collides sharply with one of these finger-beings, the other finger-beings flinch.

The flatties would have problems understanding the nature of these finger-beings that had appeared in their world; at one level they behave naturally, just like flatties, but at another they are super-natural.

Now I am not suggesting that this picture is mappable to our understanding of the Trinity, but nevertheless there are similarities, and the key thing is that the flatties experience the super-naturalness of finger-beings simply because these finger-beings are operating in extra dimensionality.

It is therefore hardly surprising that the Creator God should be able to appear (with all the attributes of a human, made in His own image) in His own Creation and, moreover, that His nature and personality should be over and beyond that of human beings.

Thus, I contend that a doctrine such as the Trinity, is reasonable on purely physical grounds, without any theological considerations whatsoever.