I rambled on about the decline of religion, but I think Pepper hit the nail on the head. Years ago, people would have been ostracized for deny a deity existed. Today, nobody gets all that bent out of shape over it. People can show their true feelings about religion.
I've said at times, "There is no god," knowing full well that such a claim calls for support which is impossible to offer. But that response is a reaction to the constant proselytizing by theists who claim to know there is a god because of bla bla bla. It's not a part of my personality that I'm proud of that when I get annoyed with bullshit, I tend to mirror more bullshit back at the annoyance. It's a poor way to argue, because bullshit doesn't deserve an argument. Nor does it need a reflection of bullshit. But in more polite discussion I should have replaced the word "bullshit" with the phrase "unending lists of logical fallacy."
First, few atheists in serious discussion make the claim that there is no god, although I've known a handful that do, and I've listened closely to their arguments, but none of them convinced me. While they may be excellent reasons to doubt the existence, they don't rise to the level of proof I would require, just as no theists has ever offered me similar proof.
Second the claim "I don't believe in God," does not equate to, "There is no God," and does not require proof.
I simply don't believe in God, and that means exactly what it says and nothing more.
It seems to me that many theists incorrectly jump to the conclusion that, "I don't believe in God," displays the same amount of conviction as their belief, which so many of them claim to be actual knowledge. As if experience or their personal revelation equates to "knowledge" and is independent of any possible flawed perception.
Or possibly theists believe the opposite of religious belief has to be the opposite belief, when opposite of any belief is just the null quantification (an empty space) (no belief).
Of course there are as many different kinds of theists as there are people, and the above cannot apply to all theists. A majority? I don't know. It seems like a majority to me, but maybe the annoying ones just stand out.