‘Another deficiency of these proofs for the existence of God lies in the fact that even if their validity should be beyond dispute, they prove too little. What is the gist of the proofs? It is the claim that given certain facts of experience, such as the rational order of the universe, God is the necessary hypothesis to explain them. Since a conclusion cannot contain more than what the premises imply, a god derived from speculation is at best as much as our finite knowledge of the facts of the universe would demand namely a hypothesis. From a rational justification of our creed, we may gain the idea that the existence of God is as probable as ether in physics or phlogiston in chemistry, a hypothesis that can easily be refuted or rendered superfluous by a change of premises. Furthermore, granted that the existence of a being endowed with supreme genius and wisdom has been demonstrated, the question remains: why should we, poor creatures, be concerned about Him, the most perfect? We may, indeed, accept the idea that there is a supreme designer and still say: “So what?” As long as a concept of God does not overpower us, as long as we can say: “So what?” – it is not God we talk about but something else.’ (Rabbi Abraham Joshua Heschel, ‘Man is Not Alone: A Philosophy of Religion’, p. 54)
As much of an admirer as I am of Rabbi Heschel, I think there is a flaw in his criticism of arguments and proofs for God here – it seems to be a rather simplistic reading and interaction of the various proofs and arguments. So far as I know, no one really claims that ‘Proof X demonstrates God’s existence! Ha!’ Most would say that such proofs/arguments serve as pointers to God, rather than actual proofs beyond all doubt. But this is a nitpick.
Thinkers such as Fr. Stanley Jaki, whom I’ve quoted and commented on frequently here, maintain not that ‘the universe seems rational, therefore god’ (though there are some who hold to such simplistic arguments) but rather ‘an environment of belief in God as a rational God who created us in His image, which includes rationality, and created an ordered, rational universe which we are capable of inquiring into is necessary for any kind of scientific investigation’. Further, as I said above, there have never been any serious Christian thinkers who have maintained that God can be ‘proved’ in the sense most people think. For someone like, say, Jaki, science was a way to God – a way, not a demonstration, and this point is.
There have been, however, Christian thinkers who have eschewed any kind of natural theology such as Jaki would defend – thinkers such as Karl Barth, Bonhoeffer and T.F. Torrance come to mind. These would be more in line with Rabbi Heschel than Fr. Jaki – and the debate between the position of Barth’s furious ‘Nein!’ in the face of natural theology and a more positive affirmation of the subject remains one of the most interesting debates in intellectual history.