Religion, Science, and Deduction

I find it bizarre that critics of evolution who claim that science is simply guessing, and that one cannot draw conclusions about past biological evolution based in present evidences, do not see how this undercuts their own claims every bit as much, if not more so.

Religious fundamentalists, of the sort that offer pseudoscientific critiques of evolution, typically claim that God spoke to and through people in the past. They claim that this revelation has persisted or left an impact down to our own time, in the form of texts which exist today. But today, we have only the texts – the fossils of the alleged supernatural revelation, as it were.

If one cannot legitimately deduce things about the past based on present evidence, then how can any fundamentalist make the claims that they do, while rejecting the use of deduction in science, without being thoroughly inconsistent?