The key difference between creationism and evolution comes down to our certainty about everything we think we know. Think about it: if our five senses and our brains are merely the product of random, purposeless evolution, how can we be sure that they’re giving us reliable information? The thing that my eye and brain perceives as “red” might be perceived by your eye and brain as “blue,” but you call it “red” because that’s what you’ve been taught. (The colors themselves won’t actually change, since they consist of certain, unchangeable frequencies of the electromagnetic spectrum.) We have no sure way of knowing we’re talking about the same thing.
Or suppose you see a rock that seemed to have a carving on it that reads “Chicago: 50 miles.” Now also suppose you believe that those markings really are nothing but the result of random erosion from wind and rain that just appear to spell out this message. Could you have any real confidence that Chicago is really 50 miles away?
But what if you knew that every normal set of eyes and brains is designed to perceive a certain frequency of the electromagnetic spectrum as “red”? Then you can have confidence in knowing that what I see as red is also what you see as red. And what if you knew that a man had carefully measured the distance 50 miles from Chicago and then put a marker there to indicate that? Then you can have confidence that that marker is giving you accurate information.
Another difference in how creationism vs. evolution affects a person’s view of the world is in the realm of morality. If we are merely the products of random, purposeless evolution, what, precisely, do the terms “good” and “evil” mean? “Good” as compared to what? “Evil” as compared to what? Indeed, without a measuring stick (e.g., God’s nature), we have no basis for saying that something is good or evil; it is merely an opinion, which really has no weight in judging how I act or how I judge the acts of others. Mother Teresa and Stalin simply made different choices in such a world. There is no answer to the ultimate “Says who?” when it comes to determining right and wrong. And while atheists and evolutionists can certainly lead moral lives—if they were true to their beliefs they would have no reason to—nor would they have any basis to judge the actions of those they determine to have done something “wrong.”
But if there is a God who created us in His image, then we are not only created with a sense of what is right or wrong, but we also have an answer to “Says who?” Good is what comports with God’s nature, and evil is anything that does not.