The Bible was meant to be a book of faith, not one of science. I do not believe that every word of the Bible was written by God Himself as a "biblical literalist" would. Rather I believe it was written by men who were inspired by God to present a spiritual message and who explained that message with historical and poetic detail. They wrote what they believed was true, but since they were men of faith writing what essentially was a spiritual message. They used daily events, folklore, and mythology to fill out the message and help with the interpretation by anyone who may read it. As such, like Galileo, I am not surprised that the Bible is scientifically inaccurate because I look to the Bible for spiritual truths that only God can reveal, not for scientific truths that are best determined by the direct observation of nature.
This, in turn, leads me to the second reason why I agree with both creationist and evolutionist theories.
The purpose of science is to determine the mechanisms by which the universe operates, of which evolution is one, whereas the purpose of religion is to determine the meaning of the universe, its purpose for existence. As such, it is perfectly legitimate to believe that a supernatural entity created by supernatural means the foundation of space-time and the natural laws and forces that operate and control space-time, then used those very laws and forces to create the universe from the Big Bang onwards. I distinguish between the ultimate origin of space-time and the way space-time subsequently operated. Science may never be able to tell us where space-time came from, but it will be able to explain - from the moment of creation onward - where the universe came from and how it developed. Religion, on the other hand, can tell us that space-time was created by God, and offer reasons why He chose to do so.
It's also important to note that God is not bound by time, so although science may measure that it took 14 billion years for the universe to be created, God could have done that in an instant or over 6 earth days or 6 God days, whatever He wanted, and it may still look to us for all possible ways of measuring that it took 14 billion years.
Here are two great articles about Christian evolution philosophy.