To clarify the answer to the question, we must make mention of the following points:

1. Every sin has two aspects one of which relates to the act of defiance or disobedience (an oppression committed against God) and another relates to the sinner cum other individuals of society (oppression committed against people and the sinner).[1]

2. Keeping in view the various circumstances in which a sin is committed, the sins and the sinners are not at the same level and they do not get the same treatment.

For example, the Quran, addressing the Holy Prophet's wives, says: "O wives of the prophet! whoever of you commits an open indecency, the punishment shall be increased to her doubly; and this is easy to Allah."[2]

Imam Reza (a.s.) has been reported as having said; "He who commits a sin openly or makes it known to others is wretched and he who conceals his sin will be forgiven."[3].[4]

3. In another categorization, the sins are divided into two kinds – the rights of God and the rights of people – and it has been narrated that: "God never forgives [the sinner who does not fulfill people's rights except for when the owner of the right (he whose right has been violated) exempts him."[5] Thus, the sins that relate to human rights are never forgivable through prayers and repentance of the sinner or other people irrespective of whether forgiveness is sought during the sinner's lifetime or after his death. Unless the people whose rights have been violated give their consent and exempt the violator of their rights he remains liable to divine punishment. For example, if a person has usurped another person's property or caused it to perish, God will not forgive him unless he whose right has been violated exempts the sinner or forgoes his right.

4. The sins are divided into minor and major ones. A major sin is a sin, which according to Islam, is so important that it has not only been strictly forbidden but God, the Almighty, has also promised to punish the sinner. These sins include fornication, murder of an innocent person, receiving usury etc. as stated in the narrations.[6] As for a minor sin, it is a sin that has been forbidden only.

The Holy Quran has promised to forgive the minor sin. It says:

"If you shun the great sins which you are forbidden, We will do away with your small sins and cause you to enter an honorable place of entering."[7]

According to the holy verse, if a person abstains from major sins, his minor sins will also be forgiven. However, it should be noted that under certain circumstances, the minor sins change into major ones and the sinner will be subjected to punishment in Hell.[8] That is, most of the minor sins change into major ones whose perpetrator God has promised to punish.[9]

5. The sinners are divided into two groups:

a) Those who commit sins on account of ignorance and lack of knowledge in which case he is forgiven after he turns to Allah with regret and repentance. God, the Glorified, has promised to forgive those who repent and make up for their sin. The divine promise is fulfilled exclusively in regard to them.[10]

b) Those sinners who commit sins knowingly and do not seek repentance will not be forgiven. There is no doubt that divine forgiveness will not include them.

It is clear from the above that divine forgiveness and any change in the situation of the sinners are possible only with those sins which God has promised to forgive after the causes for forgiveness has been made available.[11]

As for how a person who has been deviated and committing sins throughout his life is forgiven with others' invocation and good deeds, we should say that it is not true with all deviated and sinful people; the situation of all the sinners will not change with others' prayers and invocation. In fact, there are some sins which God has promised to forgive even with others' prayers and good deeds because God says, "the good deeds[12] wipe out (the effects) of the bad deeds."[13]

It does not make a difference whether the sinner himself does good deeds to wipe out the effects his sins or someone else does good deeds and dedicates its reward to the sinful person. Good deeds, as indicated in the traditions, wipe out the sins and their effects.

We have many traditions which says that when a person passes away from this world, and others (like his sons or other people) do good deeds such as prayers, fasting, Hajj, Sadaqa, freeing a slave etc. and dedicate the reward of these actions to the deceased person, the rewards of these actions will reach him.[14]

Certainly, if the reward of the good deeds done by another person and dedicated to the sinner is plentiful enough to wipe out the effects of the sinner's sin, it will make up for his sin also. Divine justice requires the sins committed by the sinner to be wiped out by the good deeds that serve as worthy compensation. God, the Exalted, has opened this way [to the servants of God] on the tongue of His Prophet (pbuh).[15]

 In this world also, if a person commits an offence and harms another person, and if a third individual reimburses him for the damage, he will surely be satisfied and if he is not satisfied, others' will reproach him. Therefore, one should not wonder and question as to how the sin of a sinner who has died is compensated by other people's good deeds.

Definitely, if a person has been committing so many sins that even if all the good-doing people pray for him and dedicate the rewards of their deeds to him, they will not make up for his numerous sins, in this case, his sins will never be forgiven with others' good deeds; rather his sins will be reduced and that God will consider some concession for him.[16]

It should be noted that since God, the Glorified, is Just and Wise and He does not commit any oppression against any of His servants and does not waste their rewards, it is likely that God may forgive those whom we consider to be sinful and entitled to punishment (because we are not fully aware of their actions and deeds), but God has knowledge of everything and He knows things which we are unaware of. If he forgives someone, it should be because of the good deeds which we have no knowledge of.

It should also be noted that since invocation and seeking forgiveness for others are often because of the positive aspects and good deeds which they have done, otherwise, if there is someone who does not have a single positive point in his life and that all his life has been full of sins, no one including his relatives will pray sincerely for his forgiveness. And if his relatives themselves are bad people, their prayers will not be answered and if they are good people, they do not remember any good thing about him so as to pray beseechingly for him.

When it comes to the consistency between verse 21 of Chapter Tur which says "And (as for) those who believe and their offspring follow them in faith, We will unite with them their offspring and We will not deprive them (of the fruit) of aught of their works" whereas the offspring has not made any endeavor and also the prophetic tradition according to which whoever performs a good deed, the fruit of their good deeds reach his children and the verse which says "there is not anything for man except what he achieves through endeavor", they are reconcilable. According to the Quran, man does not deserve to get more than what he earns through endeavor and efforts. However, it does not mean that Gods' bounties will cease to reach him through divine grace and favor. Being entitled is one thing and divine grace is another. If a person does a good deed, God bestows him rewards ten folds or hundred folds of the good deed.

Besides this, intercession is not something easy to achieve. It also needs some endeavor and spiritual communion with the intercessor.[17] Also as to the joining of the offspring of those who dwell in Paradise, the Quran says that they will join them only if they follow them in faith.[18]

In regards to intercessions, Allamah Muhammad Hussein Tabatabai says in his Tafsir al-Mizan: "In other words, when he wants to get a reward without doing his task, or to save himself from punishment without performing his duty, then he looks for someone to intercede on his behalf. But intercession is effective only if the person for whom one intercedes is otherwise qualified to get the reward and has already established a relationship with the authority. If an ignorant person desires appointment to a prestigious academic post, no intercession can do him any good; nor can it avail in case of a rebellions traitor who shows no remorse for his misdeeds and does not submit to the lawful authorities. It clearly shows that intercession works as a supplement to the cause; it is not an independent cause."[19]