Well, religion does change enormously, but the changes are often denied, minimised, covered-up - in the sense that they are falsely justified, etc. However, this is change is rarely done for purely altruistic purposes - more for survival, if anything else. Science, on the other hand, changes for the sake of self-correction, for the sake of greater accuracy and veracity. Sure, there had been people who advocated pseudosciences, but there is always a bad bunch in every nest - and the pseudosciences were not quite accepted in the mainstream, not by a clear majority at the very least (this is speaking very broadly, gah...). And whether you like it or not, eugenics does make sense from a purely scientific viewpoint.

Religion, is dogmatic, as Beskar noted, and any change should be negative, according to the dogma itself, since everything had been revealed and dictated in the very beginning.