Is it important to the Faith whether the creation of the world took place in the span of six literal days, or in epochs spanning millions or billions of years? Some seem to think that it is not. The important thing, they would claim, is simply affirming the fact that God was the divine creator. Aside from that the details are not all that important.
But I would affirm that they are. If you affirm evolution as a viable theory into which one must fit the creation of the world, several problems present themselves:
1.) The normal reading of scripture is made to bend to the current scientific understanding. Reason is placed over revelation.
2.) The uniqueness of man as a special creation made in the image of God is compromised. Man 'happens' instead as a process. He develops from something else as a progression of events. He appears on the the stage of cosmic history not as a deliberate act of a divine being, but because he was allowed to happen as a consequence of other actions.
3.) The doctrine of sin is compromised. According to Genesis sin occurs because a man and a woman made a conscious decision to violate God's will after being tempted by the devil. At what point in man's development over these great spans of time does man become responsible for making a conscious break with God's law? Surely one cannot hold a sub-human creature responsible for sinful actions, especially if they are unable to understand what that will is. Furthermore, do those who embrace evolution, and take Genesis in a strictly symbolic fashion, believe that God specifically revealed his will; that he delineated actual boundaries that separated right and wrong? And at what point was this done? Did God start holding man responsible many years after he came to be? Also, with the doctrine of sin compromised, we know that the entire doctrine of salvation also is altered.
I fail to understand how one can effectively combine an evolutionary theory and the revelation of Holy Scripture without doing injustice to Holy Scripture. Scripture and its teachings always have to take a back seat to accommodate the evolutionary view.