There's nothing in our design that makes sin inevitable. We "can by nature do the things contained in the law" (Romans 2). God made all men upright, but they have sought out their own inventions (Ecclesiastes:7:29). We were created "for Thy [God's] pleasure" (Revelation:4:11) - not for Satan's pleasure. The Bible clearly says that our bodies were not designed for sin (I Corinthians 6:13). Sin is contrary to our design, and that is why it hinders our longevity, minimizes our potential, and spreads misery. On the contrary, if we exercise our bodies and our faculties in accordance with our design and God's will, "Happy are ye" (John:13:17).
If an addiction has brought the sinner into slavery to his habit, the sinner still came under that yoke of his own choice. "He that committeth sin is the servant to sin" (John:8:34). Peter's epistle testifies that a man is brought into bondage by that which overcomes him. "Know ye not, that to whom ye yield yourselves servants to obey, his servants ye are to whom ye obey, whether of sin unto death, or of obedience unto righteousness" (Romans:6:16). The moral nature of a liar, a thief, a drunkard, and an adulterer is acquired through "yielding," and thus, the sinner is responsible.
If someone is truly unable to comply with a command, then they have no obligation to comply. Our obligation is to "love the Lord your God with all" - if "all" isn't enough to fulfill the requirement of the law, it's not the fault of the one loving, it's the fault of the unjust standard. If I instruct my child to take the trash out to the road within two minutes, and, through no fault of his own, the bag rips and trash spills, it would be unjust to blame him unless there was carelessness on his part. We all know that morality respects intention. A just moral code squares with our nature and ability. A just moral code is fit for the way we are designed. If a moral code commands of men that which is impossible or contrary to our design, such as insisting that we grow six inches taller at will, or flap our arms to fly over a building, or run 100 miles per hour, no sane person would consent that an obligation to comply exists. If someone is truly unable to comply, they are "with excuse" in the court of just law. If my two-year-old son truly is unable to drive my car around the block, then he is not obligated to do so even if I command it, and if I were to command him to do so, that would be unjust and tyrannical. All sane men and angels know this. Might doesn't make right. Just because I can punish him for doing that which he could not help but do (like wreck my car), that doesn't justify it.
Jesus taught that the state of heart is voluntary, and outward acts flow from our state of heart (Matthew:15:17-20). "Either make the tree good, and his fruit good; or else make the tree corrupt, and his fruit corrupt; for the tree is known by his fruit" (Matthew:12:33-35). The root is the heart, and the fruit are the outward actions; if our outward actions are sinful, it is because our heart's not right with God. "Circumcise therefore the foreskin of your heart" (Deuteronomy:10:16). "Make you a new heart and a new spirit, for why will you die, Oh house of Israel?" (Ezekiel:18:31). "Purify your hearts" (James:4:8).
--Dr. Patrick Johnston (“Refuting What Calvinists Believe with What Calvinists Know”)