There are a couple things that people never seem to address: 1.) Creationism is a novel idea. Believe it or not, the idea of treating the beginning of Genesis as a geology textbook is largely scoffed at in antiquity. It was the during the Protestant Reformation of 16th century Europe that the idea first gained the sort of traction it has today. (Martin Luther, the founder of Protestantism, went as far as to call writers like St. Augustine "heretics" for denouncing those who preached it as science.) 2.) There are several creation stories in the Old Testament. The first one found in the Bible is the seven-day creation story (which, according to Pope Benedict in his book A Catholic Understanding of Creation and the Fall, was written by Jews in the sixth century BC as an ideological counter to the Babylonian creation epic Enuma Elish). The next story, which details Adam and Eve and which contradicts the seven-day story, comes next. The are more bits and pieces littered through the Book of Job, the Psalms, and the Book of Wisdom. That's not to say that these stories have no value. On the contrary, a wealth of Jewish theology and ideology can be found within these texts. (The significance of numbers, for example: http://en.wikipedia.org/wiki/Significance_of_numbers_of_Judaism ) I'm not trying to argue for or against on side or the other, by the way. I just wanted to point out these peculiarities.
It might help to clarify. It's a fairly new word in the common vernacular, so if you mean "modern creationism" (fundamentalism and Creation Science) then of course it's later than the American colonial and pioneer era, which is very recent in all of church history. And if you mark it at the Scopes Monkey Trial that puts it even later. That's a curious way to put it, since geology and textbooks are fairly recent. But certainly there was some disagreement and discussion among scholars of antiquity concerning the pitfalls of literal interpretation. The real issue is fundamentalism, which distorts its history and fails to connect the evolution of religious ideas leading to their brand of creationism. I wasn't aware of the pope's book, but this indicates that he was far better educated than we must assume any fundamentalist is. Also note that the two creation myths revolve around two different gods: Elohim (the pantheon of gods) and Yahweh (the personal God). Without the strict literal interpretation by Fundamentalists, this kind of discussion would take any entirely different tack. They are forcing the issue, which is of course moot. It's just a myth. Fundies won't entertain this discussion (and no doubt Benedict's views would just give them more reason to rail against the papacy) because they have no sense of their own history. It's not exactly right to stereotype them as ignorant people insofar as there are quite a few who are also educated. But there is something deeply lacking in their education, or they would not assimilate ideas in such a fallacious manner as they do.
There seems to be something missing beyond education. That is generally the case it seems but there are a few very educated scientists who know the facts and yet cling to the "young earth" idea simply because their religion tells them so. There are statisticians who make mistakes in logic at home that they wouldn't make at work. It's an odd aspect of the human mind. In general, however lack of education does seem to account for it in most people.
