I once saw a bumper sticker that derided religion by saying "The Bible was written by people who thought the Earth was flat". Now, I'm not here to defend the accuracy of the Bible nor the religion itself, but to bring up a point about believing in a flat planet.
Algebra was invented by people who thought the world was flat, as was most of the basis for science as we know it today. And why shouldn't they have believed that? There was no proof at the time that the Earth was a sphere. Their eyes told them it was flat. Their sense of balance told them it was flat. Even walking up the tallest of mountains wouldn't dispel the idea of the Earth being a plane. Sure, you could see a slight curve on the top of Everest, but that's not enough factual evidence to show that yes, Virginia, we live on a giant ball of mud.
Eventually, more and more math started pointing to a spherical planet. Facts started leaking in and eventually it was discussed in polite company that maybe the world wasn't flat and you couldn't just sail off the end. A couple of well known sailors went in a big circle to show they didn't drop off, more math came up, and before you know it most people started to agree with it.
Enter the church. They put a LOT of stock into the 'fact' that the Earth was both flat and the center of the universe because they felt it tied in nicely to God's love of us. In fact, they put too much stock into that concept because when the facts started coming in, they did a pretty good job of killing off those who promulgated the heliocentric view of the universe. *UPDATE* I am conflabulating here… The heliocentric view was what was fought by the church, not round world. Same concept, but being lazy I didn't separate my thoughts here. Sue me.
Eventually, though, science won. Even the church agreed that the Earth was a giant sphere, that we revolved around the sun, and hey, God still loves us. People realized that hitching their faith on a wagon that wasn't going anywhere wasn't a good idea, nor did it actually impact their faith anyway.
To this day, there are still people who cling to the belief that the Earth isn't a sphere. No matter how much evidence you provide them, the Earth is Flat / Hollow / an Inverted Torus etc. They even have a non-profit organization. It's called the Brady Campaign.
You see, all the factual evidence in the world won't stop those who are anti-gun from continuing to believe that violence can be lowered if only everyone would just give up their guns. They keep making new laws that have no effect, so they make more laws. When the simple statistics and logic are brought up showing that increased gun control does little to curb crime and that criminals still continue to flaunt the law, they go an pull more and more 'data' and try to confuse the issue with statistical noise and outliers.
Just like the hollow / flat / torus Earthers can use extreme mathematical concepts to 'base' their beliefs on (even though they don't prove much at all), anti-gunners do the same thing with crime numbers, assuming that crimes only happen because of guns. They've put all their stock into the idea about violence and crime being tied to the gun even though the facts show it has nothing to do with it.
We're still in the dark ages in that respect. The "church" hasn't come forward and said "Never mind. Violence is still bad and we realize that guns aren't actually the cause of it. We can still come out against bad violence and embrace the fact that people defending themselves isn't a morally wrong concept".
Still, the evidence is overwhelming. The logic is clear. However, generations upon generations of people being taught that the Earth is Flat is hard to overcome when they don't understand the math required that proves or aren't able to be shown first hand that the Earth is round. The same goes for the anti-gunners. Most people simply take it on faith, and it can be a little difficult to deal with the cognitive dissonance that comes from having your worldview shaken by reality, but that's the job ahead of us.
I look forward to the day when people like Paul Helmke and Josh Sugarmann are treated the same as those who believe the Earth is as flat as a pancake.