Quite positive. Often they are angry at some personal abuse done to them by a church, and that is understandable, and I would feel the same in their position.
Some atheists are absolute jerks, but I don't think it's bc of their atheism:-P.
If anything, they may be more self-aware - not always - bc they are forced (to a greater degree) to wrestle with matters such as who am I and what am I doing here, that religious people should also very much do but some are lazy and do not:-).
They're generally fine, occasionally insufferable, and nearly always preferable to any religious zealot.
I'm friends with some atheists and a LaVeyan satanist (which is technically an atheist) and they're amazing. They attend weddings (and behave like they're having the time of their lives on the dance floor), have no problem participating in religious practices (e.g. prayer before an event), doesn't even bring up their belief unless asked, and are very respectful of other religions even if that respect isn't always reciprocated.
Sa internet lang ako nakaka-encounter ng dipshit atheists (particularly on Reddit), and they're honestly more insufferable than the most cockshovingly arrogant fundamentalist.
