‘The fall had cosmic relevance, but not in the sense of destroying the investigability of a rationally ordered contingent nature.’ (Stanley Jaki, ‘The Roads of Science and the Ways to God,’ p.135)
The above quote I take to be true – we are capable of investigating the physical reality in which we live. The question of natural theology, however, is whether or not such inquiry can, apart from revelation, lead us to God.
Theologically, I think the answer is a firm ‘no’. While the heavens declare the glory of God, they are not God. St. Paul makes the point in his letter to the Romans that because of mankind’s propensity for sin (the heart turned inwards upon itself, to borrow language from the Reformation) such inquiry instead of leading man to God leads man to worship creation instead of God and to the denial of God. Man’s natural knowledge of God (to borrow from Calvin, his sensus divinatis) which would lead to a knowledge of and relationship with God under ideal circumstances, has been damaged by sin:
‘…Aquinas suggested that in response to the faint whispers of the sensus divinatis, humans might respond by positing an ultimate natural principle. That is, the sensus divinatis might be the cause of our belief in laws of nature. Scientists often speak as if natural laws – like the law of gravity – cause objects to behave in a certain way; yet natural laws…are merely our descriptions of the way objects behave. Perhaps this is an example of Paul’s words, “They exchanged the truth of God for a lie, and worshipped and served created things rather than the Creator.” Like all idols, these laws might simply be placeholders for God.” (Mitch Stokes, ‘A Shot of Faith to the Head,’ p. 53-54)
The point being made is that natural theology, apart from revelation, given the inward turning of the heart upon itself from sin, cannot lead us to God – to paraphrase Kierkegaard, the truth must come from outside man.
This is not to suggest that God cannot work through a study of nature to effect someone’s salvation – it is to make the point that a purely natural theology apart from revelation cannot lead one to a knowledge of and relationship with God. Science can be a road that leads to the way to God, but it cannot be the way to God, simply because God is not a scientific principle to be arrived at via reasoning but rather a Presence which must be sought with all the heart, soul and mind.