Why do some religious thinkers disagree with Darwin's theory?

According to my belief in The Bible, God created all of creation in 6 days. Darwin's theory contradicts this theory in that creation evolved in a series of millions or possibly billions of years. As a creationist, I believe that the world has only lived for only some thousand or tens of thousands of years, but not millions or billions of years. Also, evolution's belief of rock layers defining periods of time is being proved wrong as examples of small floods show that many layers of rocks and sediment can be created through a period of a couple of hours. Believing that the atmosphere contained most of the water in the time before the great flood, the release of that flood would have created devastating results and for canyons, mountains, valleys, and innumerable layers of rock and sediment in a matter of a day. This world is too complex to be created by chance and mutation. This world was created by my all-powerful and loving God.