“Let not sin reign in your mortal body.”
It is a great evil to accustom ourselves to evil. A habit of sinning is a fatal chain which binds the soul and renders it a slave to crime. It blinds the spirit, hardens the heart, stifles the voice of conscience and gives a death-blow to modesty and virtue. The oftener we sin, the less pain we feel in the indulgence of it.
At first we regard the sin by which we are tempted with horror, then with fear, and soon with more assurance; in a little while with complaisance; then we begin to take pleasure in it and, ere long, to glory in it; after which we sin with contempt and indifference and excite others to do the same. This last state is the profoundest abyss of iniquity and the extremist degree of malice.
A man who does not feel the miseries of a sickness which is destroying him is sick unto death. A sinner who grows old and hardened in his sins may be regarded as a diseased man whose life is almost despaired of. He is unconscious of his malady.
If he desires conversion, it is only for a moment and in appearance only, and unattended by the slightest effort. His will is without effect, his desires without execution and his resolutions without perseverance. His evil inclinations come from nature, and his vices from habit.
When an evil habit gains the mastery over a soul, it is almost impossible to overcome it. It is like a torrent that sweeps away all that resists it; it is a tyrannical law which domineers over his will; it is a second nature more corrupt than the first.
Grace attacks in vain the heart that sins through habit. Its most vehement blows fall disregarded and are without effect. It is insensible to the touches of Divine love, impenetrable to its arrows and impervious to its light. It is difficult to convert an inveterate sinner. It would be easier to tear up a tree from the earth than to tear from the heart a deeply rooted vice.
How miserable is he whom habit has rendered worse than nature, more hardened, more insensible! If such a one felt the evil that is destroying him, there would be some hope of his final restoration; but while he is callous and insensible to his miseries, he is without remedy.
But let not those despair who still desire to be saved. God does all things well and nothing in vain; it is He who inspires this salutary feeling. He expresses by it His desire to save and His will to deliver everyone who will, without delay, cooperate with Him in His designs for his salvation.
This article is taken from a chapter in The Soul Sanctified: Catholic Wisdom on the Way of Salvation.