When what they really want is to be able to "believe" whatever made-up bullshit pops into their heads (or as some authority figure instructs them to). To them, "freedom" means I can believe whatever I want, regardless of whether it reflects measurable/observable reality.
People who think like this have always existed, in every race and culture of the world, so this thinking pattern is likely part of the human genome, ergo it likely confers some type of survival advantage. It fairly eludes me as to how exactly, but it's probably only helpful as part of a collective synergistic effect, i.e. the combination of some individuals who think one way + the some who think the other way confers the survival advantage. You need both "imaginative" individuals, and "rigorous adherence to observable reality" individuals for society to thrive. I would *guess* if you studied our close cousins (and you knew how to properly study it), you'd observe the same phenomenon in their populations, and a similar breakdown in counts.
For me part, I literally have no desire to believe ANYTHING which cannot be proven through science (or at least, that I could imagine science one day being able to determine, even if it has not yet). I *actively avoid* "wanting to believe (in) things" as best I can, because it clouds my judgement and my quest for actual truth. I have no desire to make anything up. This is just how I'm wired, I've always been this way. I'm the exact opposite side of the coin from people like this congressman. People like him REALLY desire to believe whatever they want. My presumption is that somehow their brain structure and/or differs from mine, and it's probably genetically, though I'm not attached to my hypothesis, because that would be unscientific 
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