Sin is like a magnesium fire, once ablaze it cannot be readily extinguished and the usually helpful agents tend to exacerbate the inferno.  What passes today for spiritual maturity (if there is such a thing) has more to do with personality type than true spiritual vigor.  Why is this? Because of the latent power of the soul!  We a fearfully and wonderfully made.  We can exhibit great character totally from human endeavor.  But in the end the totality of our works are but filthy rags!  We kick against the goads because it is our nature to do so.  We say in our innermost being, "I can do this!"  But the law reveals our inability to bring fruition to our prideful assertions.  All have sinned, all have come up short, all have missed the mark.

Wherein is the difference?  The inclinations of the heart have changed for the heart now hates those things that are not pleasing to God and loves those things that are pleasing even though we are powerless in the flesh to prove them.  This new inclination is a sign of our new ownership!

1. That the prevailing propensity; the habitual fixed inclination of the mind of the Christian, is to do right. The evil course is hated, the right course is loved.  This is the characteristic of a pious mind.  It distinguishes a holy man from a sinner.
2. the evil which is done is disapproved; is a source of grief; and the habitual desire of the mind is to avoid it, and be pure.  This also distinguishes the Christian from the sinner.
3. there is no need of being embarrassed here with any metaphysical difficulties or inquiries how this can be; for.
   (a) it is in fact the experience of all Christians.  The habitual, fixed inclination and desire of their minds is to serve God.  They have a fixed abhorrence of sin; and yet they are conscious of imperfection, and error, and sin, that is the source of uneasiness and trouble.  The strength of natural passion may in an unguarded moment overcome them.  The power of long habits of previous thoughts may annoy them.  A man who was an infidel before his conversion, and whose mind was filled with scepticism, and cavils, and blasphemy, will find the effect of his former habits of thinking lingering in his mind, and annoying his peace for years.  These thoughts will start up with the rapidity of lightning.  Thus, it is with every vice and every opinion. It is one of the effects of habit.  “The very passage of an impure thought through the mind leaves pollution behind it,” and where sin has been long indulged, it leaves its withering, desolating effect on the soul long after conversion, and produces that state of conflict with which every Christian is familiar.
   (b) An effect somewhat similar is felt by all people.  All are conscious of doing that, under the excitement of passion and prejudice, which their conscience and better judgment disapprove.  A conflict thus exists, which is attended with as much metaphysical difficulty as the struggle in the Christian’s mind referred to here.
   (c) The same thing was observed and described in the writings of the heathen.  Thus, Xenophon (Cyrop. vi. 1), Araspes, the Persian, says, in order to excuse his treasonable designs,” Certainly I must have two souls; for plainly it is not one and the same which is both evil and good; and at the same time wishes to do a thing and not to do it.  Plainly then, there are two souls; and when the good one prevails, then it does good; and when the evil one predominates, then it does evil.” So also Epictetus (Enchixid. ii. 26) says, “He that sins does not do what he would, but what he would not, that he does.”  With this passage it would almost seem that Paul was familiar, and had his eye on it when he wrote. (Dr. Albert Barnes)