I have taught my kids that both evolution and creationism are theories. Both have components that are arguable for and against. As far as I know, the Catholic Church has never come out and said how God created the Earth or man. When the Bible says that Adam was taken from the dust of the Earth. How did God do it? How long did it take? What did a day in Genesis represent? All these questions are not answered by Faith alone. Science and scientific testing of various theories can help man obtain a better understand of how God works. The strict evolutionists are just as anti-science as the strict creationists. The fact is that nobody alive today was there when God created the Earth. So any ideas that we have are just educated guesses. The Bishop is right that the Church must be open to what it can learn from science to better understand how God wove His creation. There is no denial of God in evolution as long as man accepts that all creation was guided by God throughout - IMHO.
Creationism is not a theory. It is a belief system.