Don T. I want to echo your sentiments about the right of people to have an opinion without ad hominem brickbats thrown at them.

The question is are atheists really atheist, in other words, are they sincere?
There are some who are and some who are not, just like any other group of people
who purport to have similar views. They are not monolithic.

The question asks another implied question, do atheists really exist or are they some form of aberration? This is a disguised brickbat aimed at non-religious people. Yes, they are real. One might ask the question of any religious order, are Catholics, Protestants, Jews, Muslims, Buddhists really what they purport to be? Are they real?

This is of course ridiculous. Of course they are real as are atheists, non-theists, or the new category, apathists (don't give a damn one way or another) attributed to Frans de Waal.