Theology is the study of God. Natural theology is the study of God conducted solely by natural reason. Reason is the use of the mind to think things through, using our sense experience and the laws of logic. Natural reason is that reason which man can perform without the use of supernatural aid – without divine revelation. Therefore, natural theology is the study of God conducted solely via that reason which man can perform without the use of divine revelation. Thus, the truths of natural theology apply to all men, regardless of their culture, their language, their ethnicity, their upbringing, etc. Just as the laws of physics apply to all, the definite truths of natural theology apply to all – including all claims to divine revelation.
Thus, natural theology is breathtakingly exciting. It's an adventure of the mind's use at its highest level, into the greatest metaphysical question it can probe into and ponder of – that of God's existence and His relationship to the world.
However, with natural theology, as with any exciting adventure, there will be challenges. The primary difficulty is one which afflicts those "educated" in the systems set up by "education experts" since approximately World War II.
The primary weakness of the modern mind is of precisely that attribute of the mind which is most necessary for thinking about God: reasoning in the abstract while staying logically sound.
The best analogy I can come up with for now is that of swimming. At first, a novice swimmer's lungs are not yet well developed; she must rise frequently to take breaths. However, if she is diligent in her practice, she will soon find that she can stay underwater for longer. As her lungs strengthen, she finds herself freer underwater. Our minds' capacity for abstract reasoning are our lungs; the exciting world of thinking about God is the underwater. As we immerse ourselves for longer periods of time in that kind of thought, we will find ourselves more used to it – until, soon enough, it becomes nearly second nature.
VII. The worldview sketched out by natural theology is good.
VIII. If you don't yet grasp natural theology, keep trying; it's worth it.