Feelings of remorse and guilt are natural reflections of sinning, if the person who has sinned has a conscious which is alive.
After committing a sin, a person who fears Allah and give high respect to Him would feel a sense of despondency and despair thinking, "How will God forgive me for this sin?" However, it is noteworthy that despairing of God's mercy is in itself one of the major sins in Islam for God is ever merciful, ever forgiving.
As He says in the Qur'an:
"Do not despair of God's mercy; He will forgive you of all your sins".Qur'an (39:53).
In another verse, Allah says:
"And He wishes to forgive you" Qur'an (4:146).
Islam fully understands the temptations that come in the way of everyone of us, and that which some of us might go for. Only through repentance, that one can wipeout those sins and past misdeeds and gradually get freed from the clutches of the ego.
Repentance is the most noble and beloved form of obedience in the eyes of Allah the All Mighty. He loves those who repent. Repentance has a status that no other form of worship has. This is why Allah is extremely happy when a servant repents just as a traveller is happy when he finds his lost mount in the desert.
Feeling Allah's satisfaction has its great impact on the heart of the one repenting. Hence, the repenting person reaches the status of being amongst the beloved through his repentance.
Moreover, repentance brings about humbleness and a sense of helplessness to the only Creator; Allah, and that is not easily acquired through other forms of worship.
Allah says in the Qur'an:
"Except those who repent, have faith and good deeds, those Allah will charge their sins for good deeds. Certainly Allah is most forgiving and merciful." (Qur'an 25:70)
This is a greatest glad tiding for those who repent and combine their repentance with deep faith and good deeds.
Repentance breeds good deeds, whilst sinning (without repentance) can cause deprivation of obedience altogether. It has been said that committing sins regularly will darken and harden the heart and make purifying it once again a difficult mission. It may even lead a person to reject Allah completely (Allah forbid) or lead him to commit a bigger sin. There is no recourse for a sinner except to ask Allah for forgiveness and to feel great regret for his actions.
Repentance is to repent from the heart, to train the heart into obedi ence and to make a firm resolution never to commit the sin again.
How to repent?
For repentance to be accepted by Allah, one should go through these four stages:
1- Stop the sin.
2- Regretting deeply and truly for the sin you committed.
3- Return to Allah for forgiveness.
4- Strong intention never to return to that same sin again.
What would help in fulfilling the above four stages?
The repenting person should remember three facts:
1. The grave consequence of sins.
2. The painful punishment for sins and
3. How week a person is when committing such sins.
Abu Bakr Al siddiq (May Allah be pleased with him), narrated:
"I heard Prophet Mohammad (PBUH) saying: ‘There isn’t a man who, when he commits a sin, rises, makes ablution, and offers two rak'as of prayers, but Allah forgives his sins.’
Allah says in the Qur'an:
"Those (are the true believers) who, when they commit an evil deed, or wrong their souls, remember Allah, and seek forgiveness for their sins - and who but Allah forgives sins? They do not insist upon the sins they have committed, and they know (that Allah is forgiving)." (Qur'an 3:135)