The 17th and 18th centuries saw the rise of the Age of Reason. Vast improvements in mechanical engineering and the understanding of physical laws led to the belief that all things, from the human body to the Universe itself, was entirely mechanistic.
For what is the heart but a spring, and the nerves but so many strings, and the joints but so many wheels giving motion to the whole body. ~ Thomas Hobbes, Leviathan
Rene Descartes played a crucial role in applying mathematics to the physical sciences, proposing a system in which matter and motion obeyed natural laws. However, he was quick to maintain that this did not remove the need for a Creator.
We may well believe, without doing any outrage to the miracle of creation, that by this means alone all things that are purely material might in course of time have become such as we observe them to be at present. ~ Rene Descartes
This led to the rise of Deism, the idea that a Supreme Being created the universe, set it in motion, then left it alone to function through its own laws and mechanisms. The Divine Being neither intervenes nor is interested in the affairs of the created order. In the words of Thomas Kuhn (in The Copernican Revolution): In the clockwork universe, God appeared to be only the clockmaker, the Being who had shaped the atomic parts, established the laws of their motion, set them to work, and then left them to run themselves.
This also led to the role of God being reduced further in the classic ‘God of the Gaps’ view – in which God is only postulated to play a role in phenomena in which science has yet to provide a naturalistic explanation. Such a view is apparent in the writings of Isaac Newton, who postulated the laws of motion and gravity.
So then gravity may put the planets into motion but without the divine power it could never put them into such a circulating motion as they have about the Sun, and therefore for this as well as other reasons I am compelled to ascribe the frame of the system to an intelligent agent. ~ Isaac Newton, in his second letter to Richard Bentley, a clergyman who consulted him regarding the Newtonian system
Is the ‘God of the Gaps’ view tenable today? As science discovers more and more about the world and the Universe – from the big bang to the evolution of the Universe and life on Earth, we find God being pushed further and further into obscurity. Creationists and Intelligent Design proponents often fall into this trap whenever they try to look for processes which science has not yet been able to explain and then ascribe it to the divine action of God.
As John Polkinghorne says in an interview with Krista Tippett in the radio program ‘Speaking of Faith‘ – People could see with hindsight, that the God of the Gaps type argument, the God who has stepped in to do the things that science couldn’t currently explain, was in itself a theological mistake. If there is a God who is the Creator of the world, that God is the God of the whole show. Not the sort of cosmic stunt artist who does the difficult things, the obscure bits, and leaves Nature to do the rest. It’s back to this fundamental mistake of believing that if Nature does it, we don’t need God. God is the God who ordains Nature, who works through Nature as much as through anything else.
It has again brought home to me quite clearly how wrong it is to use God as a stop-gap for the incompleteness of our knowledge. If in fact the frontiers of knowledge are being pushed further and further back (and that is bound to be the case), then God is being pushed back with them, and is therefore continually in retreat. We are to find God in what we know, not in what we don’t know; God wants us to realize his presence, not in unsolved problems but in those that are solved. That is true of the relationship between God and scientific knowledge, but it is also true of the wider human problems of death, suffering, and guilt. ~ Dietrich Bonhoeffer, Letters and Papers from Prison