The biggest problem with determining whether we have free will or not is, how could you tell?
How can you tell the difference between actual free will and apparent free will? Kind of by definition, apparent free will looks like free will, even if it isn't.
You can't determine free will by actions. And heck, free will does not even mean the ability to make decisions. Watch a robot, it constantly makes decisions. How can you tell that those decisions are programmed or not just by watching? You certainly can't. And when it comes to your own decisions, how can you tell whether they are really free? You can feel like you have a choice, but in the end, whatever you choose, was there really an option to choose? How can you tell?
I would never say we don't have free will, but I can also confidently say we don't and can't know if we do. So any attempt to use free will to try to explain something is ultimately lacks a foundation.
"Why does God allow evil?"
"Because we have free will."
"How do you know we have free will?"
"Because if we didn't, then God would be bad for allowing evil. Since God is good, we must have free will...."