Throw a monkeywrench in their plans, take a kid shooting.
Their arguement is entirely emotional based and that kind of arguement only holds sway with the ignorant. Of course logic and education best ignorance, hence take a kid (or even an anti) shooting. Whether or not they become firearms enthusiasts, they will forevermore look at the anti ads in the same ridiculous light that the rest of us do.
Taking kids shooting is very important. There need to be more kids out there at these ranges. A kid, a 10/22 and a huge box of ammo, and you can both have fun all day long, while providing an important education and life experience to boot. Bring the wife and make it a family outing!
This really is the best way to respond to drivel like this. Do it and let them know you do it; tell them for every propagandist ad they release, you will take so many kids shooting and teach them safe shooting and how sacred the 2A is.
If you don't have kids (who would have friends that would like to go shooting) then join the NRA and write a lot of letters. Do that too even if you have kids I guess. Talking about it on here is fine and all, but doing something about it is better.
I just joined NRA (I had to do it to join a local range, but meant to do it for years). I write lots of letters. I vote. I educate. I try to do my part.