Logic in an atheistic worldview

[OtisTheMarsupial]

If you're really so curious, take an epistemology class so you can learn some of the "standard" views of how both theists and atheists alike claim to know anything.
Or maybe bother to read some books.

There are as many answers for how we know as there are people claiming to have answers. And then there are the few and far between, theist and atheist alike, who know they know nothing.