"From very early days theologians distinguished what they called 'the Two Books of God,' namely, Nature and Scripture (later called 'General and Special Revelation.'). Without faith in Christ, and without the Bible as a guide, we cannot read nature to enhance our knowledge of God's power, wisdom, and goodness. Because it takes faith and the Bible to read nature's revelation, the contemplation of nature as a great gift and a revelation of God's power, wisdom, and goodness is clearly not an attempt to prove God's existence from nature. Hence such contemplation should not be dismissed as natural theology by theologians, not thought to be impossible because philosophers...." p 18 PT.
I think Allen's trying to say that without God's revelation of himself to us, we wouldn't really be able to know Him. But, He has revealed Himself to us both through Scripture and Nature (His two books). We shouldn't dismiss natural theology because God can choose to reveal Himself to us through nature. Although, Modern Philosophers do a good job of disregarding the possibility of learning about God from nature. This should not stop us from growing in our faith through Nature, because we also know faith through Scripture.
One of my favorite professors from the Concordia University of Wisconsin, Dr. Angus Menuge, has edited a book that discusses this very subject (it includes articles by some of the best current minds in theology such as Nancy Pearcey, Henry Schaefer III, and Nathan Jastram.). The book's called Reading God's World: The Scientific Vocation. He will also be editing the next volume of Philisophia Christi which will cover the topic of ramified natural theology (natural theology attempts to show that nature is proof that there is a God while ramified natural theology attempts to show that nature is proof that there is a God and specifically it is the Christian God).
"Science depends on religious assumptions and will likely lose its way without them." p 12, Menuge's Introduction.
"The scientist can pursue this knowledge in worship of the Creator and to serve his or her neighbor..." p 12 Introduction.
"Reformers, especially Martin Luther, emphasized the priesthood of all believers.... A scientist was a sort of priest, worshiping in the temple of God's world.... The scientist was called to interpret what God had freely written." p 13 Introduction.
For one example, Nancy Pearcey talks about Johannes Kepler. "He enrolled in the university to study theology, but at the end of his studies his dreams came crashing down when university authorities suddenly transferred him to a teaching position in mathematics and astronomy. Over time, however, Kepler became captivated by these subjects and came to see that science, too, can be a calling from God--just as much as the ministry. | 'I wanted to become a theologian; for a long time I was restless,' Kepler wrote years later. 'But now I see how God is, by my efforts, being glorified in astronomy,' for 'the heavens declare the glory of God.' Kepler had discovered that science is a genuinely Christian vocation. In one of his scientific notebooks, he broke spontaneously into prayer: | 'I give you thanks, Creator and God, that you have given me this joy in thy creation... See I have now completed the work to which I was called. In it I have used all the talents you have lent to my spirit.' | ... He often described astronomers as 'priests of God' in the book of nature." p 24 How Science Became a Christian Vocation (Chapter 1).
Buy the book here: