Evolution of Creationism
Language and custom change unpredictably; therefore scriptural text and interpretation change at random. Some of these random re-writings and re-readings are more fit to their society than others; those which are tend to replicate themselves in the next generation better. Over generations, the most-fit random change prevails.
This is a form of Darwinian evolution by variation, inheritance, and natural selection. Or, as the evolving religions prefer to call these forces; individuality, tradition, and the free market.
Creationism has clearly evolved in just this fashion, and within recent history. Its denial of the evolutionary process that brought it into being is a paradoxical part of what makes it fit. But for what?
For survival; that is the one constant in any evolutionary process. Adaptation is eternal; but any particular adaptation is negotiable. Thus a species can go from water to land, or from four feet to two; and a faith can go from pro-slavery to civil rights, or from anti-usury to pro-capitalism.