The bible was written in the days before science, when everybody believed that the earth was the center of the universe and that the sun, moon, and stars all circled it in the heavens. They believed that the stars were pasted onto the firmament by God. They believed the heavens were fairly close to the ground, so close that they could even build a tower to reach it. They believed God controlled the motions of the sun, moon, and stars. If God wanted to, he could even stop their motion, as he is described as doing in the Old Testament so that his people could finish their marauding.
So it was not at all hard to believe that God could have created the earth in six days and that the earth is only a few thousand years old. There was certainly no evidence against it.
But today, in the space age, we know better. We can actually observe and measure things like the age of the earth or the earth's orbit around the sun. We can tell from observation and mathematics that the stars are not simply lights hung on a firmament but are actually far away suns. We know precisely how big the earth is and how big the sun is and we know it is a million times bigger than the earth.
But we also know a lot more than that. We know for a fact that stars are clustered into galaxies and we know that galaxies are all moving away from each other. We know that, far from being the center of everything, the sun and earth are not even the center of our own galaxy of stars. We know that if you look at a piece of the sky the size of a dime held at arms length with a powerful enough telescope that within that tiny section of sky can be seen hundreds of thousands of distant galaxies.
God did not make the universe for us. That notion came from the day when everybody thought we were the center of God's creation, back when it would have made sense for a creator to have created us all for his own amusement.
Most modern Christians do not hold on to those old ideas of six-day creation. More than half believe that life on Earth evolved, although most say it was with the hand of God guiding that evolution. But at least those are the Christians who don't turn a blind eye to the facts and evidence.
But some Christians, the evangelicals, still hold to the ancient notion that God created the earth for us in six literal days. They still believe that the earth is no more than a few thousand years old. And they still refuse to believe that living organisms have evolved and are still evolving.
But to hold on to such a belief requires that these people turn a blind eye to proven facts. It requires they remain closed to accepting the scientific evidence that runs contrary to their archaic beliefs.
Creationists are fond of quoting the long odds that would allow humans to have evolved by chance. But what about the even longer odds that the predictions made by scientific theories have been proven accurate? Take for example the big bang theory. Back in the 1950s a man by the name of George Gamow predicted, through manipulations of Einstein's equations, that if the universe was actually created in a big bang then that primordial explosion would have left a microwave fingerprint in the sky. Not only that, he could tell us the properties of this radiation. It should, in fact, have a black-body temperature signature of 2.7K and it should permeate the sky in every direction equally.
In the '50s, scientists were working on Quantum Theory and didn't have time to fool around with measuring cosmic microwaves, so Gammow's prediction went untested for about 10 years. But in 1965, two scientists working for Bell Labs on a completely different project accidentally discovered the cosmic microwave radiation that Gammaw had predicted. When other scientists over the years verified their discovery, they were awarded the Nobel Prize. Not only was the radiation coming from all directions equally, but the temperature of it fit precisely with the mathematical prediction made by Gammow years earlier.
So, either the universe really was created in a big bang, or the precise temperature of the universe, 2.73K just happened to be exactly what a scientist predicted by accident. It could have been any temperature at all, but it turned out to match the prediction exactly.
This is just one isolated example of many, many such examples of science predicting measured reality. Evolution theory, Quantum theory, the Big Bang theory, the Theory of Relativity, etc. all have made astoundingly accurate predictions about nature. Intelligent Design or Creationism have not made a single verifiable prediction about nature. Yet evangelical Christians believe wholeheartedly in them and denounce proven theories such as the big bang or evolution.
The proofs of science can be verified by anyone with the right equipment and enough knowledge. There is no secret club you have to belong to or oath you have to take to be a scientist. You simply have to follow the scientific method: Ask a question and search for the answer by following protocols designed to eliminate bias. And then once you find the answer, you have to accept it even if you don't like it.
That's what science is and that's the advantage it will always have over religion. The things we, as humans, now know boggles the mind. A few hundred years ago we were just beginning to come to terms with gravity. Today, we know (and can show we know it with mathematics and observation) what the exact temperature of the universe was a millionth of a second after the big bang. Plus we know that there was, indeed, a big bang. These things are no longer just speculation. We KNOW them and can prove them, to anyone who cares to listen.