Hi,
I am not really technically atheist, but I was once and some may even argue I still am. So allow me to answer your question:
I sometimes believe in free will and sometimes I don't. Sometimes I do something really random to show that could not possibly have been determined. Let me do something random now. I will say 10 words now at the top of my head:
fire, girdle, monkey, time, space, load, orange blue, juice, green
Those words were completely random, or so they seem! I cannot really think of any connection between fire, girdle and monkey. However, there does seem to be connection between time and space and load. There is definitely a connection between orange, blue, juice and green. I tend to say fire and monkey a lot(I call my dog monkey brains lol) though I don't really say girdle, except maybe I just said girdle because I was trying to be random, so I said something I wouldn't normally say. Thus in all cases there definitely seems to be some determining factor. When I analyse what I say like this that's when I cease believing in free will and believe in determinism.
But it's such a conflict because I cannot give an absolute free will account or an absolute deterministic account. If everything is determined than when I do something completely random is that determined as well? Surely not, no? Perhaps there is both determinism and freedom i.e, what you do is determined largely, but there is still an element of freedom in the present. What do you think?