No, you can never be sure because the nature of the thing means there can’t be absolute proof. But there’s plenty of evidence against it and minimal to no evidence for it, so the likelihood of there being a) a god b)who gives a crap about us and c) interferes directly in people’s lives is infinitely tiny. It is quite infuriating, though, when the religious in this country have the power to legislate based on theology that not everyone shares. Why do people care if gays get married, for instance? If one believes this will send them to hell, then fine, but for those of us who don’t believe in hell, it makes no sense. Sigh.
“Live a good life. If there are gods and they are just, then they will not care how devout you have been, but will welcome you based on the virtues you have lived by. If there are gods, but unjust, then you should not want to worship them. If there are no gods, then you will be gone, but will have lived a noble life that will live on in the memories of your loved ones.” – Marcus Aurelius