Actually, the two are connected. If you do away with God, free will eventually vanishes too, into scientific determinism. Some people think Heisenberg's Uncertainty Principle can undo the determinist dilemma and leave room for chance and choice, but it really doesn't--it only complicates it.
That is, determinism.
When someone claims to have free will, I tranlate it into English: "My outputs are not functions of my inputs."
Very well. What are your outputs functions of? Cosmic rays?
A random robot is still a robot, and Heisenberg offers no shelter.
If the universe is causal then it is deterministic.
If the universe is random then it has no room for free will.
(And yes, I am "reading" Wegner's book, and I find it difficult, tendentious, and boring.)
Personally I wish it were otherwise but there you have it.