Atheist here, who more often than not falls into your category of assholes. but am from a heavily religious family (3 knights of the holy sepulcher) .
For some us religion and faith as a structure for learning and personal development have been catastrophic. Critical thinking is not possible( I know I'm generalising, sorry) in religion. Parents, like in religion, use the ''because I said so''. The child learns that things are the way they are because god said so as if everything is independent from anything else. It becomes very hard for a child to learn in school when he has to memorize each piece of information instead of learning things organically.
Regards to Mocking : Mocking/ being humors is necessary for discussion, thus why we have political satire entertainment.
how to flip off an atheist getting up in your religion: you believe in evolution? good. Evolution happens over thousands of years. A species has many genes, some more obvious than others. Chickens are reptiles, reptiles have teeth and chickens don't so the gene that gives chicken teeth is dormant.
Now, there is something known as the god gene, that ( if you decided to accept as fact) gives you a predisposition to have supernatural beliefs. From an evolutionary perspective this gene helped humans servive over thousands of years thus why it is present (need source here)
If someone believes in somethings, it might because they have the gene that helped there ancestors survive. so this leaves us with two points. 1) The atheists are bigoted for mocking you for something you might have been born with, so your belief isn't even your fault, so according to the atheist's logic, he is being rude. 2) Genes changing takes thousands of years to change so arguing about it like you're going to change the world in a few years is disillusion. Let evolution take its course and be compassionate towards your fellow man. ALWAYS remember the economics of happiness, (Happy society performs 2% better on average, so always be nice)