Negative Effects of Atheism

I'll take neither.  Agnosticism is the only truly scientific belief system.  After all, to know that you don't know is the very basis of all scientific discovery.

I am an atheist, and I know I don't know.  Agnosticism in its most useful form is the idea that we don't and can't know whether a god exists.  Therefore, you can be an agnostic atheist like me, or an agnostic theist.  It's not a scale that goes from theist to atheist with agnostic in the middle.  Agnostic is a separate question altogether. 

Atheism/theism answer the question "Do you believe there is a god?".

Agnosticism answers the questions "Do you know there's a god" and "Is it possible to know whether there's a god?".

I believe there is no god, but I wouldn't say I know it, nor do I think we'll ever know for sure.