I believe that the doctrine of the Trinity is essential (in the sense that it is most consistent with) a theology of love. The Bible says that God is love. I am of the school of thought that LOVE is God's core characteristic. Indeed, all other 'attributes' of God are simply His love playing out in context. I believe belief in the Trinity is part and parcel with this theology.Disclaimer: I am not one to insist upon a certain understanding b/w the relationship b/w the Father, Son & Spirit as a test of orthodoxy, BUT I also believe the best way to find truth is to boldly put a belief out their and subject it to scrutiny. In this post I will be using bold language to make a case for the doctrine of the Trinity...
The Father, Son & Spirit are, and always have been, a loving relationship. In trinitarian thought, love is not just something God does... love is something God is. God is a loving relationship. There was never a reality where only the Father existed. If such a time had existed, love could only be at best a potential attribute to be displayed at some future date.
In Islam, for example, God is rigidly one. He created, primarily, in order to have creation submit to Him. How could love be a core characteristic for Allah if, before creation, He was without relationship entirely? Likewise, how could the Christian God have love as a core characteristic without any essential relationship? The Christian God is love. The Christian God is the loving relationship b/w Father, Son & Spirit.
Technically, my view could be maintained with some modification from 3 to 2. What is essential is that the concept of 'God' is made up of loving relationship (whether that be b/w 3 or 2), but I see no reason to reject the vast majority trinitarian position.
In my opinion, it is time we stop ignoring the concept of trinity as a mysterious concept. It is time we stop thinking of it as an important peace of doctrinal information that has no real effect on our lives. The Trinity means that God IS love. God-love becomes the core concept of Christianity because of the reality of the Trinity.