It’s easy to think that those who oppose various scientific findings – like creationists or flat-earthers – don't understand something about science.
This basic assumption is known as the deficit model: people are mistaken because there's something missing. To help them become un-mistaken, then, we need to provide what is missing. Perhaps better education or better communication – about geology, about biology, about physics, about logic, about evidence, about mathematics, something.
But, in many cases, these anti-science crusaders are not missing something crucial about science. Rather, they have something else that they are deeply committed to. They can engage in all of the arguments that scientists can. And they can do so with sophistication, subtlety, and wit. It’s just that they also have commitments that conventional science advocates lack.
Although creationism now spans the globe and crosses denominational – and, in some cases, even religious – boundaries, the origins of creationist thought lie squarely in a handful of Christian sects and their members' commitment to the inerrancy of the Bible as a historical record.
In the late 1700s and early 1800s, European scientists studying earth's origins were nearly all committed Christians. As the 19th century progressed, and the mountains of evidence – geological, biological, and, eventually, chemical – piled up, many leading scientists had to reconcile their faith in the Bible as a record of events with the many astonishing signs that the earth was very, very old and had a long history of biological change and cataclysmic geological upheavals. By the late 1800s and early 1900s, almost everyone studying earth origins or biological change accepted the idea of a very old earth and long processes of evolutionary change that shaped the biological and geological record.
A handful of scientifically and religiously inclined men, however, persisted in believing that the Biblical record, as they read it, was correct, and the scientific evidence – or the interpretation of that evidence – must be flawed or mistaken or misunderstood.
The intellectual leaders of the creationist movement were not stupid and – with some minor exceptions – they were not fundamentally ignorant of the existing scientific evidence. The main difference between them and their secular contemporaries was simply about assumptions: the intellectual leaders of creationism took it as axiomatic that a "plain" reading of the Biblical record was true – no, that it had to be true. As such, they had far more intellectual work to do than their secular counterparts.
With such a commitment, many questions come up. What pieces of scientific evidence support the Biblical record (and, therefore, should be promoted) and which pieces of evidence contradict the Biblical record (and, therefore, should be attacked)? How should one interpret the Biblical text? Few creationists believed that the earth was the center of the universe or the solar system, as implied in several Bible verses, and many creationist leaders, because they were committed to scientific principles, actively avoided associating themselves with such "kooky" ideas. How should one resolve conflicts and ambiguities within the Bible itself? How should different theories about earth's origins, derived from the Bible, be meaningfully tested? What should you do when scientific evidence and Biblical implication contradict themselves?
It's easy to think of the creationist movement as a monolith – as presenting a single, unified view of earth's origins. But it's only because of advocacy and organizational efforts that outsiders perceive it that way. Internally, the intellectual leaders of the creationist movement struggled mightily with each other – and within themselves – to resolve the hornet's nest of questions presented when trying to reconcile both the Biblical record (at times contradictory, ambiguous, and incomplete) and the large body of scientific evidence (itself, also, at times contradictory, ambiguous, and always incomplete).
A common secular attack against the creationist position is that it assumes the hypothesis that creationists seek to prove. There was a single flood event. It was important. The age of the earth cannot be more than 10,000 years old. Fixed "kinds" of animals (of some sort) were created, or even, "designed".
But what appears, from the secular scientists' point of view, as an intellectual flaw, is, to the scientifically minded creationist, an intellectual virtue. "We take this revealed framework of history [of the Bible] as our basic datum, and then try to see how all the pertinent data can be undersood in this context." (p 232, Numbers, quoting The Genesis Flood by Whitcomb and Morris). "If the Bible is inspired then we must accept its assertions regarding the early history of our earth as major premises." (p 321, Numbers, quoting Frank Lewis Marsh and P. Edgar Hare, emphasis in the original)
The deficit model is not always wrong. But major disagreements often have their roots in assumptions, premises, and epistemological commitments – not in the simple ignorance of facts.
I'm drawing heavily from Ronald L. Numbers fantastic history of creationism. Numbers in parantheses above come from the 2006 edition, cited below.
Numbers, R. L. (2006). The creationists: from scientific creationism to intelligent design (No. 33). Harvard University Press.