Why are atheists generally more pessimistic about the futur than christians ?

on what do you base this assumption

I don't see it that way. Given that my life before death can only be all the experiences I will ever have, I remain highly optimistic about planning and executing my personal future. Sadly, the historical persistence and decidedly negative impact of organized religion leaves me pessimistic about humanity's long term future. What kind of future can a civilization ever achieve when a majority of its citizens habitually deny reality and wallow in superstitious ignorance? ...little beyond more of the same.

I'm not pessimistic about life at all. I'm quite optimistic and plan to live every minute to it's fullest.

Your statement is a gross generalization based on an ignorant narrow minded assumption.

Presuming that we actually are (which is a big presumption given that you could have easily just said that without any basis at all), the most rational explanation would be that we have to actually live in the real world as it presently exists. We can't just shrug off suffering as some step to an eternity in paradise. And death is real to most of us, not mitigated by platitudes of, "Oh, she's gone to a better place."

But then neither are we riddled with guilt for very silly things that a storybook character supposedly wants from us...

I'm not more pessimistic about life than an average Christian. Why would you assume I am?

I would say that having no religious beliefs actually makes me more optimistic about my life. I know it's the only one I'm going to get, so I'm determined to make it the best I possibly can. There's no point wasting it being pessimistic.

Because 'Christians' have killed millions of people worldwide in the past, so why would the future be any different?

While I may be realistic, I am not pessimistic.

lol you have a large group of christians babbling about the rapture and the tribulations and the coming end of the world--and this is optimism?

And who are you to make such a claim? I am happy as can be and greet each new day with a smile, while my christian parents sit around waiting to die because they view this life as worthless. Nice try.

Because that's how the future is, and atheists are not blinded by overly fantastical fairytales unlike their religious counterparts.