Then what are you doing on a Conservative Forum?
Why do you support the Constitution and the Bill of Rights if free will is not guaranteed?
Because there is every appearance that free will does exist so it is rational to proceed as if free will exists, even if it hypothetically might not.
Stated differently, it appears far more likely that free will exists than that an omnipotent, omniscient god exists.
Rationally, there are two options:
1) Free will exists: proceed as if free will exists.
2) Free will does not exist: no decision is yours to make.
Since free will appears to exist, even if it does not, then one should rationally proceed accordingly.