Traditional Christian theology has been based upon the proofs for the existence of God. The presupposition of these proofs, psychologically if not logically, is that God might or might not exist. They argue from something which everyone admits exists (the world) to a Being beyond it who could or could not be there. The purpose of the argument is to show that he must be there, that his being is ‘necessary’; but the presupposition behind it is that there is an entity or being ‘out there’ whose existence is problematic and has to be demonstrated. Now such an entity, even f it could be proved beyond dispute, would not be God: it would merely be a further piece of existence, that might conceivably not have been there — or a demonstration would not have been required. ¶ Rather, we must start the other way round. God is, by definition, ultimate reality. And one cannot argue whether ultimate reality exists. One can only ask what ultimate reality is like — whether, for instance, in the last analysis what lies at the heart of things and governs their working is to be described in personal or impersonal categories. Thus, the fundamental theological question consists not in establishing the ‘existence’ of God as a separate entity but in pressing through in ultimate concern to what Tillich calls ‘the ground of our being’.