I received a question from a student of mine via email just after Christmas, and they wanted to learn the Church's position on a literal or figurative six-day creation as presented in the book of Genesis.
"How does the Catholic Church view the creation story that said the world was made in 6 days? Was it meant to be taken literally or was it symbolic for a larger time frame?"
This is a matter of personal faith. On the one hand we know we have God, an almighty and all knowing creator whom with all things are possible. God can do anything. So with this philosophy it is not unreasonable to believe that God could have created the world in six days (and Him resting on the seventh) or six days as we know them.
On the other hand, even though scripture (the Bible) tells us that the world was created in six days, was anyone there to witness it? No, of course not! So how can we believe the creation stories in the book of Genesis? It is reasonable to assert that these stories were generations older than the first of Abraham's people, and it was not until much, much later that someone decided to write down these accounts. It was not as if someone had quill to scroll (i.e. pen to paper) as these unique and individual events took fold.
The key thing to understand here is that every tribal culture has tribal stories, meaning that a tribe or culture will have stories that explain how things came to be, great events that took place within that people and stories that pertain to that group of people in particular. For example, the Australian Aboriginals have "Dreamtime" stories that explain how the birds got their colours, why the emu bird doe not fly, how particular star formations took shape, and so on. These stories, as well as other tribal stories, are not scientific and were creative ways for people with limited understanding of how things work understand how things came to be. We call this "mythology".
To understand the creation stories in Genesis, it's very important that we divorce the word "mythology" with its common or contemporary definition, and that is to parallel the word to "made up" or "make believe"
The word "myth" comes from the Greek word "mythos" which means "story" or "word", and we know the creation accounts in the book of Genesis to be creation stories. Basically, this is how generations of believers have explained and understood how the world and its inhabitants came to be however many years ago.
No one can ever fully understand the intricate details behind the creation of the world, even someone with an advanced scientific knowledge of physics or cosmology. We do know this, however:
You can't create something from nothing, therefore there has to be a creator.
Back to the question: literal or figurative six days?
The Church does not specify or instruct us to believe in one or the other, so it is a matter of personal faith. In fact, believing in the literal or figurative six day creationism is an issue that separates many Christians on an individual basis. What the Church does tell us about creation, however, is this:
"Among all the Scriptural texts about creation, the first three chapters of Genesis occupy a unique place. From a literary standpoint these texts may have had diverse sources. The inspired authors have placed them at the beginning of Scripture to express in their solemn language the truths of creation - its origin and its end in God, its order and goodness, the vocation of man, and finally the drama of sin and the hope of salvation. Read in the light of Christ, within the unity of Sacred Scripture and in the living Tradition of the Church, these texts remain the principal source for catechesis on the mysteries of the "beginning": creation, fall, and promise of salvation." - CCC 289
We know that the truth of creation is found within Sacred Scripture, and believing all that is written within scripture requires faith: believing what is not seen. We are free to believe in a literal six day creation, or whether the number of six days is figurative. As Christians we are invited to investigate, using both faith and reason (understanding) to seek the fullness of truth in creation, examining all that is revealed to us with a faith-driven scrutiny; a desire to understand; a yearning of the human heart for truth.
The Six Days of Creation (Jimmy Akin) - http://www.catholic.com/thisrock/2003/0301bt.asp
You Can't Make Something From Nothing! (blog post July 31, 2009) - http://thespiritmagnus.blogspot.com/2009/07/you-cant-make-something-from-nothing.html
Evolution (John Salza) - http://scripturecatholic.com/evolution.html