I agree with you and would maintain that atheists could easily be less happy and more neurotic than religious people. And I use the word "happy" loosely, because true happiness is unalloyed and therefore when someone is happy "about" something it is impermanent and dependent; therefore it may easily turn to unhappiness. Such is the case, for example, when an atheist is forced to face death (not in all cases, of course, but as a possibility) and he questions whether there really is a god (foxhole argument). Or when a religious person faces tragedy and questions whether there is a god at all (good examples include many Holocaust survivors I've read).

I have often wondered how happy my life would be if I did not think about things very deeply and loved all kinds of sports, watching vapid TV shows, having a nice car, fully trusting the government and institutions, and believing that spirit guides, angels, and God were always watching out for me and my family. Instead, I find all of this to be conditioned, delusional thinking. The kind of happiness from such an existence, as we have seen, is conditioned so that when the conditions change so too does the state of happiness.