Most people believe that sin is a problem of capacity. They believe that sin is the manifestation of a fault in capability. In reality, sin is a fault of desire.
In this life, God gives us the power to choose.
27 Wherefore, men are free according to the flesh; and all things are given them which are expedient unto man. And they are free to choose liberty and eternal life, through the great Mediator of all men, or to choose captivity and death, according to the captivity and power of the devil; for he seeketh that all men might be miserable like unto himself.
28 And now, my sons, I would that ye should look to the great Mediator, and hearken unto his great commandments; and be faithful unto his words, and choose eternal life, according to the will of his Holy Spirit;
29 And not choose eternal death, according to the will of the flesh and the evil which is therein, which giveth the spirit of the devil power to captivate, to bring you down to hell, that he may reign over you in his own kingdom. (2 Nephi 2)
Obedience to God is a choice. In this world, we can either choose good or evil. Those who choose good will be saved. Those who choose evil will not.
11 Now, concerning the state of the soul between death and the resurrection—Behold, it has been made known unto me by an angel, that the spirits of all men, as soon as they are departed from this mortal body, yea, the spirits of all men, whether they be good or evil, are taken home to that God who gave them life.
12 And then shall it come to pass, that the spirits of those who are righteous are received into a state of happiness, which is called paradise, a state of rest, a state of peace, where they shall rest from all their troubles and from all care, and sorrow.
13 And then shall it come to pass, that the spirits of the wicked, yea, who are evil—for behold, they have no part nor portion of the Spirit of the Lord; for behold, _they chose evil works rather than good_; therefore the spirit of the devil did enter into them, and take possession of their house—and these shall be cast out into outer darkness; there shall be weeping, and wailing, and gnashing of teeth, and this _because of their own iniquity_, being led captive by the will of the devil.
14 Now this is the state of the souls of the wicked, yea, in darkness, and a state of awful, fearful looking for the fiery indignation of the wrath of God upon them; thus they remain in this state, as well as the righteous in paradise, until the time of their resurrection. (Alma 40)
Most Christians do not actually desire to obey God. They are interested in obeying God, but they allow their desire for other things to dictate their sinful behavior. Desire isn’t the same as interest!
All willful sin is committed because the sinner wanted to sin more than they wanted to obey God. Many people fail to repent because they think they can overcome sin through sheer will.
The key to desire is not willpower. It is knowledge. Your beliefs are what dictate your desires, and your choice to adhere to your beliefs—to have faith in them—is the decision point determining whether or not you will sin.
The question of sin is not whether you will to sin or not, but rather why you desire what you do. What do you believe will happen or not happen due to the paths of action open to you? What do you desire, and why?
While we can choose to behave in a way that is contrary to our beliefs, most sin is tempting only because we do not yet possess the information that sufficiently illustrates the sinful choice to be suboptimal compared to the alternative.
Often, the key to conquering a particular temptation lies in trusting God enough for him to reveal to you the awful truth that shows that what you desire is not worth desiring. This often includes the violent revision of your beliefs about deep-seated aspects of who you think you are or what you think of others. This is why remaining in sin is preferable for those who love anything more than truth. The truth will set you free, but it will hurt to the degree that you cling to what you must let go of in order to embrace it.