Actually, we can have both. Unfortunately, we can’t prove both. But you can believe in both.
Here’s the deal: Creationism isn’t a matter of provable science and should never be taught in school as such. You simply can’t prove creationism. It’s a matter of faith based on your personal beliefs based on what you read in the Bible and/or what another person of faith tells you. Incidentally, you can’t disprove it, either. But you can disbelieve in creationism just as easily.
What is provable, and the longer we study it the more proof is found, is the Big Bang theory is real. Pope Francis of the Roman Catholic Church recently affirmed pretty much the same thing.
So here is my proposal: If you believe in creationism, fine. If you don’t believe in creationism, fine. But there is increasing proof that the Big Bang happened. The laws of physics provide for it. And if God did indeed create the universe and everything and everyone in it, he used the Big Bang to do it.
We cannot take the Bible’s or other religious works’ word on how the heavens and earth were created literally. If they were inspired by God, they weren’t intended to be the literal description of creation. They were a generalized account for people with no sophisticated understanding of atoms and energy and gravity and space-time continuums and the speed of light and more. The people of thousands of years ago had no idea of quantum mechanics and cosmology or even space-time dynamics, let alone the simple concepts of forces, energies, or the expansion of space. But they could understand dividing light from dark, night from day, water from land, and so on. They could understand a day as a division of labor rather than an epoch as a transition between energy states.
If there were an Adam and Eve, they must have been a special couple from among many created rather than a first pair. The story doesn’t pan out logically for extending the family line – who would Cain have married, without Adam and Eve giving birth to a girl? I look on that story, rather, as an allegory to address the dangers of thinking too highly of your smarts and the opportunity it poses of thinking yourself as smart and powerful as a god.
But back to the main point. If God created the universe, he didn’t slam it together in six short days using magic. He used natural laws that he divined in a way to make them the same throughout the universe – lasting and consistent throughout the universe. He set them out and let them take their course, taking billions of years, letting life evolve naturally to arrive at the human form – on Earth at least. To suggest that things took only 6,000 years but we see 13.7 billions worth of light years because God created them that way so you could explain away the inconsistency is saying God made mistakes he has to rework to suit your excuses, and that’s baloney.
Science studies the universe not to tear down theology but to prove the facts. The facts show a huge universe 13.7 billions old, 13.7 billion light years (or more) across, on a space-time fabric expanding and growing, with billions of galaxies each containing billions of stars. Science proves that the universe exists in a world of gravity, conservation principles, quantum mechanics, and other principles through rigorous discovery and testing. That’s the how of the universe that only science can address.
Creationism can address the why of the universe. It cannot address the how.
Similarly, science can’t answer the why, only the how.
However, there’s room for both if you have an open enough mind.