Do stereotypes have any truth to them?

[Sheldon]

My favorite is 'atheists have no morals'.

Yeah, that's certainly not justified. Lots of atheists have morals.

It's true that a lot of atheists think that morals are simply social conventions, with no objective existence. But even if a person believes that, he can still do his best to obey the conventions of his time and place. 

There's another stereotype concerning atheists I see occasionally. People who study theology seriously will make fun of what they call "Reddit atheists." These are people who 1) talk a lot about religion on line, and 2) have enormous confidence in their own reasoning power, and 3) know little or nothing about theology. And of course until quite recently they often referred to the works of Dawkins and/or Hitchens. 

This is the sort of person who thinks he has any and every Christian check-mated, while not bothering to learn much more about Christian thought than "TalKinG SnaKES!!1!" "NO MaterIAl EvidENce!!!!!"

I think we've all encountered people like that, but Reddit atheists are surely not representative of most of us. They are on line and visible by definition, while the great majority of atheists don't care enough about it to go on the Internet every day and criticize.

The word atheist is entirely redundant in that post. Poor reasoning is poor reasoning, and FYI there are theists who believe every word of the bible and Koran is literally true, it is risible to decry people who address such claims, as if they must address the 45k different sects and denominations of Christianity globally, or all the various claims theists generally make and believe, in every single discussion. 

If anyone wants to sneer at me as poorly educated they can knock themselves out, it's likely true on a wide range of topics, but I would still disbelieve claims that were unsupported by any or insufficient objective evidence. If sneering contempt is all they have, then they're likely holding an empty bag. 

This argument sounds like the tired old chestnut that one cannot disbelieve the Islamic religion unless one has Arabic as a first language. I don't need to be an expert in Bigfoot, in order to withhold belief, and the same is true of deities, from the risibly falsifiable, to complex nut ultimately vapid arguments that can must not one shred of objective evidence that any deity exists or is even possible.