The will is the power or faculty by which the mind makes choices and acts to carry them out. At first, against his will, a person engages in some forbidden pleasure because he wants to, but if he keeps it up, he soon finds that he has no strength to resist it. This process does not happen any more quickly than an addiction to alcohol, but in the end, he keeps sinning because he cannot help but do so! Once a thought or act becomes a habit, it is a short step to being a necessity. The old saying is true: "Sow an act and reap a habit; sow a habit and reap a character; sow a character and reap a destiny."
Hebrews 3:12-13 reveals a worrisome characteristic of sin: "Beware, brethren, lest there be in any of you an evil heart of unbelief in departing from the living God; but exhort one another daily, while it is called 'Today,' lest any of you be hardened through the deceitfulness of sin." Sin is seductive, enticing, deceitful, and hardening.
Sin's deceitfulness is that it cannot deliver what it promises. It deludes a person into thinking he can "have it all" or "take it or leave it." It promises pleasure, contentment, fulfillment, and life, but what it delivers in those areas is fleeting, which leads to its addictive quality. The pleasure is never quite enough to produce the desired contentment and fulfillment. Sinners are forced into greater perversions until it kills them.
Sin offers rationalizations and justifications. It puts on a plausible appearance and can even seem to be virtuous, as in situation ethics. However, sin's drug-like quality always demands more because what formerly satisfied no longer will. The person in its grip gradually becomes its slave, and all along the way, his heart becomes hardened as well.
In Hebrews 3:13, hardened is translated from the Greek word for a callus. A callus forms around the break in a bone, on the palms of hands and on fingers from constant hard use, or in a person's joints, paralyzing its actions. In a moral context, it suggests "impenetrable," "insensitive," "blind," or "unteachable." A hardened attitude is not a sudden aberration but a habitual state of mind that shows itself in inflexibility of thinking and insensitivity of conscience. It can eventually make repentance impossible.
Jeremiah 9:1-5 describes people in this state, so inured, so enslaved to sin that they weary themselves pursuing and doing it:
Oh, that my head were waters, and my eyes a fountain of tears, that I might weep day and night for the slain of the daughter of my people! Oh, that I had in the wilderness a lodging place for wayfaring men; that I might leave my people, and go from them! For they are all adulterers, an assembly of treacherous men. "And like their bow they have bent their tongues for lies. They are not valiant for the truth on the earth. For they proceed from evil to evil, and they do not know Me," says the LORD. "Everyone take heed to his neighbor, and do not trust any brother; for every brother will utterly supplant, and every neighbor will walk with slanderers. Everyone will deceive his neighbor, and will not speak the truth; they have taught their tongue to speak lies, and weary themselves to commit iniquity."