The "desire to sin" is alien to the human race, and only entered in through Adam's disobedience. Sin, in this sense, is that resident indwelling desire to fulfill our own lusts - whatever they may be. It is that well from which springs our anger, jealousy, etc. Normally a person has no power to change these desires, since they do not spring from himself, but from the sin that is within him - he can only choose to obey these desires or deny them.This is why Paul, in Romans six talks about "obeying sin" - he is talking about giving into the internal desire to sin.Now - that internal desire to sin is not human - or at least not originally human - but something that came into humanity through Adam's disobedience - I repeat this because it is important to understand that the desire to sin is what is producing death in people - and it is what Christ came to destroy.The Pharisees make a great example in this discussion. The Pharisees were religiously motivated men. They believed in God, and didn't want to go to hell - so they went about trying to obey God's law. They practiced a strict disciplined life whereby they suppressed sin - such that the outside of their cups were clean - that is, whenever they had a desire to sin, they didn't follow it through, but through supreme acts of self will, they suppressed that sin - they didn't obey it. For many of the Pharisees this was as good as they could do - they couldn't stop themselves from lusting, hating, etc. (that is, they could not deal with the desire to sin, or the inside of the cup) but could only stop themselves from acting on these sinful desires. They had come to a place where they believed they were keeping themselves from breaking the law of Moses; and they thought that this was what it was all about - pacifying God by not doing what they very much wanted to do. They thought this self denial was holiness - and imagined their own righteousness and ancestry had purchased for them a place in heaven.They dealt with sin by suppressing it. The best they could do under the law was to not act on the indwelling desire to sin.They still sinned in their hearts because there was nothing they could do about it. The law could not take away the desire to sin - it could only forgive through sacrifice.Christ brought something new to the picture in that grace came through Jesus Christ. Not simply unmerited favor - any favor God had ever given mankind has been unmerited - and we have had plenty of that long before Christ - this grace that Christ gives can make powerless the internal desire to sin.So, when we ask, why do we sin - we sin because we are obeying that internal desire to sin that came into the world through Adam.The law could not deal with the desire to sin - it could only point out that sin was there. But the new covenant makes provision for this desire - this heart of stone (Ezek 36) this old man (Romans 6) - it can be taken away (rendered powerless) so that one no longer desires to sin. NOT that a person becomes better able to suppress sin - but that sin becomes weak and unable to impose itself on the believer. Not a better weapon to defeat the power of the enemy - but a disarming of the enemy so that the enemy no longer has strength to impose his will on the believer.How does one receive this wonderful grace that enables us to be free from the very desire to sin? By grace through faith. We believe that this is the promise of God, and we receive the grace that enables freedom.Now, God only gives this grace to the humble, so when we fail to receive it, we know immediately that we are not being humble before God in that moment, and we have to search and find where we were proud and exalting ourselves - then we repent of it and continue to believe that God is going to remove even the desire to do that sin.This is, as far as I know, holiness 101. Every true believer has a desire to fellowship with God, but many have not been discipled in the process of how to have fellowship with God.So why do we sin? We sin because we choose to obey sin rather than God. When we finally understand that sin is something that is killing us - we can appreciate how God loves us - because we don't see God as an angry Diety punishing sinners - we see God as the compassionate lover of our souls working tirelessly to turn us away from obeying that which is producing death in us.Dan/\\/\\/\\edited for clarity...
