The effects of sin, as described by Ibn al-Qayyim (may Allaah have mercy on him):
1 – Being deprived of knowledge for knowledge is light that Allaah causes to reach the heart, and sin extinguishes that light. When al-Shaafa’i sat before Maalik and read to him, he admired him because of the intelligence, alertness and understanding that he saw in him. He said,
“I think that Allaah has caused light to enter your heart, so do not extinguish it with the darkness of sin.”
2 – Being deprived of provision. In Musnad Ahmad it is narrated that Thawbaan said:
“The Messenger of Allaah (peace and blessings of Allaah be upon him) said: ‘A man is deprived of provision because of the sins that he commits.’” (Narrated by Ibn Maajah, 4022, classed as hasan by al-Albaani in Saheeh Ibn Maajah).
3 – Sense of alienation that comes between a person and his Lord, and between him and other people. One of the salaf said:
“If I disobey Allaah, I see that in the attitude of my riding beast and my wife.”
4 – Things become difficult for him, so that he does not turn his attention towards any matter but he finds the way blocked or he finds it difficult. By the same token, for the one who fears Allaah, things are made easy for him.
5 – The sinner will find darkness in his heart, which he will feel just as he feels the darkness of night. So this darkness affects his heart as the physical darkness affects his vision. For obedience is light and disobedience is darkness. The stronger the darkness grows, the greater becomes his confusion, until he falls into innovation, misguidance and other things that lead to doom, without even realizing, like a blind man who goes out in the darkness of the night, walking alone This darkness grows stronger until it covers the eyes, then it grows stronger until it covers the face, which appears dark and is seen by everyone. ‘Abd-Allaah ibn ‘Abbaas said:
“Good deeds make the face light, give light to the heart, and bring about ample provision, physical strength and love in people’s hearts. Bad deeds make the face dark, give darkness to the heart, and bring about physical weakness, a lack of provision and hatred in people’s hearts.”
6 – Deprivation of worship and obedience. If sin brought no punishment other than that it prevents a person from doing an act of worship which is the opposite of sin, and cuts off access to other acts of worship, that would be bad enough. So the sin cuts off a third way and a fourth way and so on, and because of the sin he is cut off from many acts of worship, each of which would have been better for him than this world and everything in it. So he is like a man who eats food that is bound to cause a lengthy sickness, and thus he is deprived of many other foods that are better than that. And Allaah is the One Whose help we seek.
7 – Sin breeds sin until it dominates a person and he cannot escape from it.
8 – Sin weakens a person’s willpower. It gradually strengthens his will to commit sin and weakens his will to repent until there is no will in his heart to repent at all… so he seeks forgiveness and expresses repentance, but it is merely words on the lips, like the repentance of the liars, whose hearts are still determined to commit sin and persist in it. This is one of the most serious diseases that are most likely to lead to doom.
9 – He will become desensitized and will no longer find sin abhorrent, so it will become his habit, and he will not be bothered if people see him committing the sin or talk about him.
For the leaders of immorality, this is the ultimate shamelessness in which they find great pleasure, such that they feel proud of their sin and will speak of it to people who do not know that they have done it, saying, “O so and so, I did such and such.” Such people cannot be helped and the path to repentance is blocked for them in most cases. The Prophet (peace and blessings of Allaah be upon him) said:
“All of my ummah will be fine except for those who commit sin openly, and that includes cases where Allaah conceals a person’s sin, but the following morning he exposes himself and says, ‘O So and so, I did such and such last night, so he shamelessly exposes himself when all night his Lord had concealed his sin.” (Narrated by al-Bukhaari, 5949; Muslim, 2744).
10 – When there are many sins they leave a mark on the heart of the person who commits them, so he becomes one of the negligent. As one of the salaf said, concerning the aayah –
“Nay! But on their hearts is the Raan (covering of sins and evil deeds) which they used to earn”[al-Mutaffifeen 83:14 – interpretation of the meaning] –
this means sin after sin.
How this starts is that the heart gets stained by sin, and if the sin increases then the stain grows bigger until it becomes the raan (covering of sin and evil deeds), then it increases until it becomes a seal, and the heart becomes covered and sealed. If that happens after a person had been guided and had understood, then his heart is turned upside down, and at that point the Shaytaan gains control over him and directs him as he wants.