Christianity has survived two thousand years. But in that time it has cast itself into innumerable forms. It has diversified and subdivided to the point where, in some cases, one group of Christians hardly recognises another as professing the same religion. Many Christians do not understand each other when it comes to expressing their faith, and there are such cultural differences in the varied incarnations of that faith that it is often impossible for one group to feel in the least at home with the other, or indeed to share at least the basic presuppositions of any degree of 'communion' with each other. Yet, Christians are all baptised into the same Body, and, in the words of the First Letter to the Corinthians, they share a cup that 'is a communion with the blood of Christ, ' and share the bread which 'is a communion with the body of Christ. The fact that there is one loaf -- the letter continues -- means that, though there are many of us, we form a single body...' This image, supplemented by others, such as the vine and the branches, indicate that, being one in Christ, as Christians believe they must be for their very salvation, is a sort of organic communion through which a single common life is shared.