Matthew 18:8 And if your hand or your foot causes you to sin, cut it off and throw it away. It is better for you to enter life crippled or lame than with two hands or two feet to be thrown into the eternal fire.
Whenever someone tells me a story of personal failure and disaster, I ask if he or she can identify how it started. No one sets out to drive drunk or have an affair and few engage in radically destructive behavior without making a thousand small choices leading up to the big one. Occasionally someone will blame his or her devastation on one poor choice, but when honest, he or she can usually identify a multitude of progressively destructive choices leading up to it.
The problem is, I think that I can get away with little sins. I think that I can indulge in my flesh nature in secret, insignificant ways that do not matter. No one will know. God will forgive me tomorrow. No consequences.
My brain works in such a way that when I indulge in something that feels good once, I am much more likely to do it again and again. I do not, when hungry, eat just one potato chip. I start out saying, Just a couple will satisfy me and then no more. After whole bag and crumbs everywhere, my conscience stings and I finally stop. Then, I promise myself that I will never do it again. After a few repetitions, this becomes an ingrained, accepted pattern of behavior. I do not like it, but I just accept that this is what I do.
Potato chips may not lead to the collapse of my career and marriage but indulgences of the flesh in little areas can lead to indulgences in more destructive ones. If, instead of potato chips, I indulge in lust, anger, pride or just one taste of a chemical, I can and will lead myself down a progressive road of destruction.
Jesus knew how we were wired when He spoke these words. He knew our propensity to tolerate our destructive behavior. Thus, He taught us how we are to deal with our flesh. We are to be ruthlessly violent with those desires of the flesh that distract us from our pursuit of God.
If I do not know what my defects are, I need only ask what keeps me from pursuing the relationship with God that I am meant to have. Am I reading, praying, meditating and enjoying an intimate relationship with God? If not, what is keeping me from him? It may be as simple as the fact that I am selfish with my time and would rather watch TV. It may be that I am tolerating destructive pursuits in my life that cause me to avoid God.
Jesus point was, whatever keeps me from my right relationship with God is destructive and needs to be violently cut out of my life. My path does not have to end in jail to lead me away from God.
To be clear, Jesus was not teaching self-mutilation. It is not my actual hand or foot that causes my destruction. His point though, was that if it truly is my hand, then it is a small sacrifice to avoid complete destruction. This is how serious I am to take any indulgence of my flesh nature. If it distracts from God, I must ruthlessly cut it out of my life. I cannot pursue life and death at the same time. If I want life, I must amputate that which brings death.