The first thing God tells us in the Bible, the foundation of all our knowledge about Him, is that He made everything. There are a lot of things He could have told us first, but that's what He chose. It's really important. It's where we have to start. We can learn a lot about an artist by studying his work, especially when we start with what he himself has said about it. Those who study the paintings of Picasso, for example, will notice the distortions in his female figures and suspect that his relationships with women were troubled. And they would be right. Similarly — and much more positively — we can learn a lot about God by studying His artwork, His creation. Theologians call that general revelation.
When we study the cosmos, we're learning about God — His greatness, His goodness, His wisdom, His aesthetic. In school we call that science, but it's really theology.
You might be surprised to realize that all objects of human study work that way. A lot of people think math, for example, is secular — that 2 + 2 = 4 whether you believe in God or not. While that might be true, it's also simplistic. Math is the study of the quantities and relationships we see in nature. I like to say it's the design language God chose when He created the universe. So math, too, is theology; it's one of our most intimate looks at how God's mind works.