I agree with you (and Keathley) about "determininsm", however, the christian theist can and should argue that this determininsm originates with God, whereas the atheist/agnostic will claim that this determinism is a necessary property of a deterministic and completely natural universe.
I would say the atheist, although not believing in God, will argue from a view of “if” there is a God He is a deterministic and despot god who brings evil into the world. They will often then fall back on P.O.E. (Problem of Evil) arguments about divine exist either being of evil or not omnipotent. A very similar argument to the Christian one except the atheist does wish the theology to become fatalistic.
Whoo! Pretty much lost me on that one...For me, and a good deal of natural scientists, the determinism of Descartes died in the 20th century with the advent of quantum physics and mechanics