‘For I do not seek to understand that I may believe (intelligere ut credam) but I believe in order to understand (credo ut intelligam). For this also I believe, – that unless I believed, I should not understand.’

This gives the key to Barth’s interpretation of the ontological argument. Anselm is not here providing an argument whose logic must convince us that God exists but rather one which is an expression of faith, in which the existence of God is presupposed. It is hardly surprising, therefore, that the argument should fail as a proof because to provide a proof for the man outside faith was never Anselm’s intention. His intention was not to deduce the existence of God from the definition of his being as the greatest conceivable perfection, so that the Fool is a fool precisely because he denies what is already implied, but rather to provide a meditation on the supremacy of God as an article of faith, in which the role of the Fool is to confirm the view that it is the believer alone who is in a position to understand.

To support this interpretation Barth points to the setting of the proofs, namely, that they begin and end with prayer, with an address to God. Given that Anselm’s critics, beginning with Gaunilo, ignore this fact, it is not surprising, Barth argues, that they have ignored the theological presupposition of the proofs and accordingly misinterpreted them as a priori philosophical deductions. Anselm’s proof is therefore entirely different from Descartes’, and so it is ‘so much nonsense’ to suppose that ‘it is even remotely affected by what Kant put forward against these doctrines’.

This interpretation of the ontological argument as an expression of faith is reinforced in Barth’s discussion of the specific arguments of the Proslogium. Take, for example, the famous definition of Proslogium 2: that God is ‘something than which nothing greater can be conceived’. This does not present, as is commonly supposed by commentators, a philosophical platform upon which to construct a logical and irrefutable proof of God’s existence, but rather provides a theological description, negatively expressed, of who God is. In this sense, therefore, the description stands as a ‘revealed Name’ of God, revealed by God to Anselm in a moment of prophetic insight, and by which he came to recognize the impossibility for faith of denying the existence or the perfect nature of the God designated by that Name. What is revealed, in other words, has less to do with the specific character of God’s nature and more to do with the limits imposed on human thought when thinking of him, namely, that it cannot conceive of anything greater.

This, Barth maintains, is the absolute rule of thought (Denkregel ) which the Christian derives from revelation and which provides the norm of all theological thinking: it is an acknowledgement of the complete Christian dependence on God’s prior communication of himself to believers. To suppose, therefore, that God could somehow be ‘proved’ would mean that men need no longer wait upon God’s self-revelation for their knowledge of his existence and that they had therefore a degree of independence from him. Neither view, however, is supported by the creator–creature relationship to which holy scripture bears witness.

source Michael Palmer A Question of God page 26