Calvin believed in free choice too. Hard to be a human without choosing freely. We merely only choose from among the things we can think of or want. And God was never something we thought about or wanted.
That would be something like me going to the grocery store to pick out something for diner. And, among my choices could have been liver.
Except, no. It couldn't. Because I already know I HATE liver, so wouldn't even see it to make the decision to avoid it, and it wouldn't come to my mind as a possibility. (I have been at the meat section in a grocery store at least once a week for 39 years, and recall seeing liver once or twice way back when. I'm sure I pass it. I just am not looking for it to see it. lol) I'm still choosing freely, but only within my perception of choices.