Libertarian Freedom
There are some people who believe in what is called Libertarian free will (hereafter called LFW), which means that a person is always able to choose or choose otherwise in a given situation. Being able to choose or choose otherwise, they argue, is the only way to be responsible for your actions. If you couldn't have done otherwise, then you are not responsible for your actions. In this view, a person is absolutely free, even from the determination and constraints of the human nature or the determination of God.
Compatibilism
On the other hand, there are people who believe the Bible teaches what is called Compatibilistic Free will (CFW). This view asserts that man's actions and choices are done freely, but are also in accordance with God's determination and control over the entire situation. Since the man acted freely, he is held responsible for his actions, and yet God remains sovereign. Compatibilistic free will also asserts that the human will is not free from the constraints or the inclination of the human nature, but in fact is a slave to it. In other words, the will does not control itself, nor does the will control the nature, but the nature controls the will and therefore your nature determines your choices.
For example, if you offer a pit bull a bowl of salad or a big juicy steak, his nature is such that he will always predictably and consistently choose the steak over the salad. In this case, the Pit bull cannot really be said to have chosen or chosen otherwise. His choice was determined by his nature. It was not a free choice in this sense, but it was free because it's what the pit bull desired to choose. His choice was in perfect accord with his own nature and desires.
So the will is determined, but it is determined by who you are. This is self-determination. This, CFWillers argue, is the very essence of true freedom.
In like manner, CFWillers say that the Bible teaches that the human nature is wholly ruined and corrupted by sin. The human heart and will are in bondage to the corruption of sin, indeed, slaves to sin and satan himself, always doing his will, until the Lord graciously moves to rescue. The fallen, unregenerate man is completely hostile towards God, finding the gospel foolishness, hostile towards Christ, at enmity with God. He "hates the light and does not come to the light". If offered salvation, he will refuse it consistently because he lacks the spiritual faculties to humble himself before the God he hates so much and give up the sins he loves so much.
The problem is deep down, it is a heart problem. The man needs to be regenerated. He needs to be quickened from death to life, raptured from darkness to light. This, only God can do, and that by grace.
In other words, mankind by nature is not "neutral" towards God, and therefore able to choose either to the right or the left. Rather, mankind is completely opposed to God, and holiness, and does not desire Christ, only desiring to remain in the sins they love, therefore will always consistently and predictably choose to reject Christ and embrace sin.
If any man is ever saved by "choosing" to believe and embrace Christ and humble himself and repent of his sins, it isn't because he is smarter, or more spiritual, or somehow able to escape the constraints of his own evil nature because he is innately better than his neighbor, it is because the Sovereign Lord graciously moved to rescue that man, change his heart, and bring him to faith and repentance, which the Bible teaches are gifts from God.
