So what do Christians have to work with? The Old Testament books, handed down for a good few millennia, then the New Testament, added when the prophecies of the Old Testament were fulfilled, and closed the book that we now know as the Bible. The only thing Christians have to work with is interpretation of this one piece of data that is never going to change.
Science, philosophy, and things of that sort, on the other hand, are subject to change at a moment's notice. Any scientist will tell you that the very nature of science is unbound, able to shake the very foundation of everything we know with the findings of even an amateur, an elementary school student, who accidentally digs up a fossil with his plastic shovel and pail. Science, therefore, is also open to interpretation, but it is also free from the restraint of dogma.
So, if in a week or year or millennia, if science happens to find out that Christians were telling the truth the whole time, that our beliefs were indeed correct, science can't be faulted for being "wrong". It's the nature of science to change, so being wrong is only a part of its (good lord give me a better word..) evolution (doh.

So we have two sides. One that stands on a firm foundation, unchanging, and another that's like a bottle in the ocean, taking it whichever way the current or wind is going.
As a matter of fact, if you look at it in the technical aspect, you have numerous different sides, because scientists almost never agree 100% with each other's interpretations. So you have these many different sides that are able to morph into anything the latest tidbit of data throws to them versus the one lonesome side that must defend themselves with a book at was finished almost 2000 years ago. How fair does that really seem to you?
Atheists expect Christians to have the answers to every nitpicked fault they find in Christianity that pertains to science, and it's just plain unreasonable. Not only that, they expect the answers on the fly, or else they crank their insult machine up and go to town.
How fair are these arguments that science keeps bringing up, when they know themselves the facts they're arguing with can change at any minute?