An atheist is one who believes that there is no deity, not one who
doesn't believe in a deity. That's an agnostic - one who is not
committed to believing in either the existence or the nonexistence of
God or a god.


Nope. An atheist lacks belief in god/gods. That's all it means. However agnosticism has a broader meaning and doesn't necessarily apply to a god belief/non-belief. Maybe this quote will help explain the difference...

"Agnosticism addresses knowledge in general; atheism addresses belief in a god specifically. As such, agnosticism is broader and more useful. It is the refusal to take as fact any statement for which there is insufficient evidence. It is a philosophy which may be applied to any area of life, whether science, UFO's, politics, or history; though it has most commonly been invoked in a religious context." --Dan Barker


-Florian