Every Calvinist I have met believes in free will, although they see it in terms of the ability to do things within one's nature:
If a person is dead in their sins, they have broad freedom to indulge in sin. They just have no ability to indulge in righteousness since that is outside of their nature. Just as a penguin does not have the ability to fly, even though he has wings, the sinner does not have the ability to be righteous.
If a person is alive in Christ, they have broad freedom to indulge in righteousness, as well as sin, because righteousness is now part of their nature through Christ. Just as an eagle can soar on their grand wings, a Christian can soar in righteousness because that is now part of their nature. That same eagle can also walk around in the mud, just as a true Christian can indulge in sin for a season, because that is still within their realm of ability even though it is not part of the new nature that Christ provides.
You can't say a person is
enslaved to their sin nature and also say they are free. That is a direct contradiction. The fact that Calvinists cannot see this direct contradiction is amazing.
Fact is, the scriptures do not say an unregenerate person is enslaved to always choose evil. Jesus himself said sinners can do good.
Luk 6:32 For if ye love them which love you, what thank have ye?
for sinners also love those that love them.
33 And if ye do good to them which do good to you, what thank have ye?
for sinners also do even the same.
Jesus said sinners love those that love them. This is not sin, you
should love those who love you. Yes, it is better if you also love those that hate you, nevertheless, it is still good to love those who love you.
Jesus also said that sinners do good to those that do good to them. Again, it would be a greater love that does good to those that hate us. Nevertheless, it is good, and no sin, to do good to those who do good to you.
If man was utterly enslaved to sin, he would always choose to do the most evil thing he can do. The fact that unregenerate men do not do this proves they are not enslaved to sin in the sense that they are
compelled to sin.
We are enslaved to sin in the sense that we are under the condemnation of the law. We are condemned to death by the law. That is how we are enslaved. When we trust Christ we die to sin and come under grace, we are no longer under the dominion of sin and death.
Unregenerate men can do good, Jesus himself said so.