I know and believe my children and husband exists and i can see the sun.
So yes atheists do have believe. And disbelief.
What has the future got to do with the current price of eggs?
So yes, in the future the sun will blitz our planet, either with a solar flare (tentative belief) or by going red giant and swallowing it, factual so believe it. By that time humans probably won't exist anyway so don't worry about it.
And what makes you question another's believe, a person you know nothing about. Seems rather arrogant to me