As an answer to a discussion question in my Historical Theology class, I posted the following-
As a trained scientist I've paid a bit of attention to this topic. I won't even try to be brief.
The Bible simply assumes the existence of God, without making any attempt to prove it. So why should we look outside the Bible for reasons for His existence? Is this attempt trying to lift nature higher than scripture? What is the relationship between nature and grace; reason and faith?
First, we should define 'natural theology'. The simplest definition I know is from RC Sproul- a knowledge of God that is gained from nature.
There are many different views of what natural theology is and means, which explains some of the controversy around the concept. It is based on 'general revelation', but is not the same thing. General revelation refers to something God does, but natural theology is something we do. Natural theology comes out of general revelation.
The audience to general revelation is universal. Not everybody has access to special revelation (at least, not yet).
The content of general revelation is also general, not specific. We can learn general characteristics of God, but not specifics, such as the nature of the trinity, and so forth.
In general revelation, we have two kinds- mediate and immediate general revelation. Mediate is that revelation that God gives to all people through some medium. It is indirect. "The heavens declare the glory of God..." is the psalmist saying that by looking at nature, we see that though the stars are not God, they display some of the glory of their maker. Immediate is the revelation that God gives to all people directly, without an intervening media. Romans tells us that God has written his law on our hearts...this is immediate and directly from God. It is not a deduction from nature. We get this inscription by virtue of being human. Calvin called this the sensus divinitatus.
Natural theology is of course most associated with Thomas Aquinas...as a result, protestants tend to view natural theology as a strictly Roman Catholic process, and thus shy away from it. Francis Schaeffer, for example, claimed that Aquinas separated nature from grace. As much as I like Schaeffer, I don't think he understood Aquinas completely enough to make these distinctions without destroying the union between nature and grace that Aquinas developed.
To understand what Aquinas was trying to do, we need to see him in his context. What problem was Aquinas trying to solve? The answer was Islam. Islam was the greatest threat to the church at this time...and was supported by powerful Muslim philosophers. They argued something called, 'Integral Aristotelianism'. (Say that fast three times!) This was a synthesis between Muslim theology on the one hand and Aristotle on the other. Their central thesis was the 'double-truth' theory. This theory stated that something could be true in philosophy and false in religion at the same time (i.e., true in science, false in theology).
[This sounds remarkably like contemporary arguments for the co-existence of evolution and theism by Biologos, by the way; and is a philosophical stance that I held in my own life for a number of years as a neo-Darwinist before God's grace revealed the falsehood of the idea.]
St. Thomas developed his ideas of natural theology in response to this double-truth theory from Islamic philosophy. He said we can and must distinguish between nature and grace. What he meant was, there are certain things we can learn from nature that we don't learn from special revelation. The bible doesn't teach us anything about nuclear physics, or molecular biology, even though the study of these things is made possible by the common grace of God on man. And while these things are to be distinguished, one cannot be true in one arena and false in the other. This would violate the law of non-contradiction.
Thomas added a third category- the articulus mixtus (mixed articles). These are things that can be learned from either the Bible or from the study of nature. Chief among these things is the existence of God (RE Paul in Romans 1). Thus, the reason the Bible does not argue the existence of God is, from the beginning, God has proven his existence beyond any doubt in nature. So Aquinas argues that the existence of God is proven both by nature and by scripture. He doesn't separate these two things, he makes distinctions.
Thomas stood on Augustine's shoulders. Augustine taught his students that they should learn as much as they could learn about whatever they could, because all truth was God's truth and would reveal God. Augustine's natural theology was based on Paul, of course.
In Rom. 1, Paul goes back to show why the gospel is necessary, and this is based in general revelation. People aren't condemned because of rejecting the Jesus they've never heard of, but because of what they've done with the knowledge of God that they DO have. This 'suppression of the truth of God' is the primary sin of fallen humanity. As Paul says, God has made the truth about himself (that may be known) manifest (phaneros/manifestum); yet we have rejected it.
The general revelation Paul speaks of produces a natural theology in us. This natural theology clearly gives us enough knowledge to condemn us. It does not give enough to save us. For that we need special revelation.
One other point is important: If God reveals himself in nature and in scripture, and the primary textbook of the scientist is nature, and the primary textbook of the theologian is the Bible, why is there conflict between science and theology? Because we live in a fallen world, we don't have complete understanding of either nature or God. Both the scientific community can correct the church (as we probed earlier in the term), and the church can correct the scientific community. But both nature and scripture reveal God, limited as our understanding in both arenas may be.
Reference- Sproul RC. Defending your faith.