One element in the first season of the BBC series Sherlock that sticks close to Arthur Conan Doyle’s original is the mention of Sherlock not knowing that the Earth orbits the sun. Here’s a clip of the scene:
This mention of geocentrism actually makes an important point. It is possible to be incredibly gifted in one area and completely clueless in another.
And this is relevant not just to the question of whether you trust a hydraulic engineer over the consensus of the world’s biologists, geneticists, geologists, astronomers, and all those in fields related to evolution or the age of the Earth.
The fact that someone is a really fantastic Christian doesn’t mean that they will have a fantastic grasp of science either. Indeed, the fact that they put well into practice what they understand doesn’t even mean that they are particularly well versed in the study of the Bible. After all, there were some really fantastic Christians who were illiterate, and/or who lived before there was a complete Bible of the sort available today, much less one that could be consulted so conveniently.
And so when considering matters of science, or history, or the study of important ancient texts, remember Sherlock. It is far better to honestly admit that some things do not matter to you, than to pretend that because you are an expert in some area, that you must therefore have a good grasp of another.