Clear thinking about humankind’s fallen nature requires a careful distinction to be made between ‘free agency’ and ‘free will’.
Free agency is part of what it means to be human. We all make decisions as to what we will do and how we will behave, based on our personal inclinations and our sense of what is right and wrong. We are moral agents, accountable to God and to one another for our voluntary choices.
Free will, on the other hand, has been defined as the ability to choose from all the moral options that may be available in a given situation. Many Christian teachers, including Augustine and Calvin, have said that original sin has robbed us of free will in this sense.
We have no natural ability to discern and choose God’s way because we have no natural inclination Godward; our hearts are in bondage to sin, and only the grace of regeneration can free us from that slavery.
According to Paul, in Romans 6:16-23, only a will set free from this bondage freely and heartily chooses what is right. See also John 8:34-36; Gal. 5:1, 13.
The will does not have a separate existence apart from my self. It is not like my hand or foot, which I can choose to move or not to move. My will is precisely me in choosing and in carrying out that choice.
The truth about free agency, and about Christ freeing sin’s slave from sin’s dominion, can be expressed more clearly if the word will is dropped and each person says: I am the morally responsible free agency; I am the slave of sin whom Christ must liberate; I am the fallen being who only have it in me to choose against God till God renews my heart.
Based on J.I. Packer, Concise Theology, art. ‘Inability’