When you look at a few pieces of art by the same person, you begin to pick out what else they have done based on the style. When you look at houses designed by a particular architect, you can see their underlying favors in design. When you look at rooms by an interior designer, you can sometimes tell who it is that decorated the place.
So when we look at creation and see things that are similar, we can conclude there must be a Designer. He has a particular style. Look at plants: while one plant is a tree and one is a flower, they work the same way. Look at animals: while one is a dog and another is a whale, they both need very similar things to survive. Look at DNA; all living things have it. And then the building blocks of all things – atoms everywhere!
This way of detecting style and design extends even to God’s direction in our lives. When God speaks, you can know His voice. When God moves, you can tell it’s Him. Our Creator has a particular way of doing things. Read the Bible and talk with Him, and you’ll learn even more! Like you do with human designers, the more you get to know God and His work, the faster and more clearly you will pick out other things that He’s done or is doing!