A Calvinist friend of mine recently asked me the difference between “unwilling” and “unable” and why I consider the two to be mutually exclusive when talking about mankind’s ability to sin or not. Here’s my reply
If I am unable I cannot be unwilling because my inability precludes my willingness either way. I know you tire of hearing it, but it’s an apt description. If I am unable then I am no better off than a robot preprogrammed to run a certain course and as such I cannot rightly be held accountable for that which I have no control over.
On the other hand, if I am unwilling then I logically have the ability to act in a manner other than that which I choose. That my actions are foreknown is not the same as saying that my actions or choices are less free. In fact, you could even say that my actions are predetermined so long as you account for my freedom to choose at some point (aka, in eternity past as part of God’s omniscience as a brute fact per Molinism).
You see, either I am truly free to choose to sin or not to sin (as the Bible teaches) or else I am unable to choose not to sin (a concept foreign to Scripture).
If I am unable to not sin then I cannot logically be held accountable or responsible for choices that are, by definition, beyond my control.
If I am unwilling to not sin then I am not only responsible for my choice but, in light of the holy standard of God, I am unable to bridge the gap I freely created.
I realize that inability and unwillingness have been tossed around the Reformed world as if they were somehow comparable but the truth is that they aren’t.
The bottom line is that we are either free and responsible or else we are not free and therefore not responsible.
Only one leaves God unstained by the sin and evil that exists in the universe since only one allows for other causal agents who had the ability to freely create and choose to sin against the will of God.