Being a Biophysicist, I work in the regime between quantum and classical mechanics all of the time. First of all, I must say I view physics as an abstraction. I don't think it completely defines reality, it just does enough to convince ourselves. And just because it convinces ourselves it doesn't mean nature obeys.
Now I don't mind discussing between free will and Einstein's god that doesn't play dice. So if reality was completely deterministic, god would only need to know the initial state of everything and what laws they obey to know entirely everything about the universe. So to human understanding that would justify an omniscient god. But this kind of omniscient god would know what everyone does before they do it and exactly on creation, so it could be said that god created people to do exactly what they do and they have no free will as everything is already determined.
To break that is to introduce a randomness, or a chaos to an extent. And in ways quantum mechanics can do it. One of the postulates is that you can have many duplicate systems starting from the same initial conditions and obeying the same laws and they will yield different measurements under a probability distribution. So in this way nature and the universe cannot be determined and has a bit of chaos that god would not know before hand every move of each person and thus resulting in a type of free will.
Now this chaos only seems to come about once one makes a measurement, or tries observing that it is there. The wave function of particles do not collapse unless you measure them. So it could be that nature is deterministic as waves until we try to meddle in things and measure it lol. But remember folks, quantum is not the end all and be all, despite the early rough reception of string theory it is getting bigger and on the verge of having predictable results.
And finally I agree with vectorcube that we should omit judgements on the matter, as obviously it is required of us to make glaring assumptions both on the scientific side and theology side to get any of it to remotely work.