Our Lord explains the kind of repentance which will gain acceptance in His sight in the verse, "Allah only accepts the repentance of those who do evil in ignorance and then quickly repent after doing it. Allah turns towards such people..." (Surat an-Nisa': 17). In another verse, Allah describes sincere believers as "those who, when they act indecently or wrong themselves, remember Allah and ask forgiveness for their bad actions (and who can forgive bad actions except Allah?) and do not knowingly persist in what they were doing " (Surah Al 'Imran: 135).
Allah tells us that He will forgive mistakes made through ignorance or lack of knowledge, provided that people immediately give them up when they notice them and do not persist in the same errors. Thus a believer who wants to achieve true sincerity towards Allah should think in line with these verses and ask Allah's forgiveness for all the insincerities he hides inside himself.
However, the behavior for which Allah will call people to account on the Day of Judgment does not consist only of the insincerities they display openly. Allah also takes into account insincerities that people are consciously aware of, but try to hide from others. As we are reminded in the verse, "... Allah knows what you divulge and what you conceal" (Surat an-Nur: 29), Allah knows what is going on inside a person even though others cannot prove any insincerity. Because of this, when evaluating himself, a person should measure not only his externally visible behavioral defects which can be proved, but also his secret insincerities. He should give up all these and ask Allah's forgiveness.
He should know that otherwise—if he does not accept warnings he is given, disdains those who give them and sets his face against them— he may fall into the situation of the people described in the Qur'an like this: "No indeed! Truly man is unbridled, seeing himself as self-sufficient. " (Surat al-'Alaq: 6-7) In such a situation, because he has not come even close to sincerity and has not changed his behavior, even though he knows Allah's commandments and sees the true path, Allah may close down his comprehension completely. Allah warns His servants about this:
I will divert from My signs all those who are arrogant in the Earth without any right. If they see every sign, they will not believe in it. If they see the way of right guidance, they will not take it as a way. But if they see the way of error, they will take that as a way. That is because they denied Our signs and paid no attention to them. (Surat al-A'raf: 146)
If people persist in their insincerities despite being warned by the verses of the Qur'an, their own consciences and sincere believers, the outcome they may suffer while in the life of the world is not limited to this. Allah tells that He may blind the eyes of the conscience of those who take no notice of the advice given them:
Such are the people Allah has cursed, making them deaf and blinding their eyes. Will they not then ponder the Qur'an or are there locks upon their hearts? (Surah Muhammad: 23-24)
These are only a few of the things that Allah can do to people who resist sincerity. Never forget that Allah is the Almighty Who created everything. If He wills, He can increase people's torment in the life of the world. He can bring the secret troubles that people suffer because of their insincerity to a level at which they take over their identities completely. If He wishes, Allah can make the world too small for people.
In the Qur'an, we are told that in the past, many peoples submitted to Allah and directed themselves towards sincerity in the face of such a torment.
It is He Who conveys you on both land and sea so that when some of you are on a boat, running before a fair wind, rejoicing at it, and then a violent squall comes upon them and the waves come at them from every side and they realize there is no way of escape, they call on Allah, making their religion sincerely His: "If You rescue us from this, we will truly be among the thankful." (Surah Yunus: 22)
In this verse, Allah tells us that when they are helplessly trapped amidst waves in the middle of the ocean, people devote themselves to Him, "making their religion sincerely His."
What makes these people adopt this sincerity is being in torment and, understanding Allah's power and might, seeking His help. Strikingly, at such a point, people are not forced to try for sincerity at all. At the moment they see the torment, they use their consciences and their wills to the maximum and make every sincere effort to achieve a morality that Allah will approve. This demonstrates that, even before they experience torment, people possess the power to be sincere. There is really no need for others to explain to them or try to prove their insincerities. They can take on characteristics that Allah will approve simply by referring to their consciences. If despite this, they still set their faces against those who warn them and invite them to sincerity, they should seriously fear the torment that Allah can bring down on them in the life of the world.
Allah can repay people for insincerity with torment at any unexpected moment. He can take away all a person's goods, property and respect and leave him in helpless poverty. He can bring down unimaginable discomfort, unhappiness and inner affliction. While keeping the body alive, He can petrify the soul so that to the end of his life, the individual can take no pleasure from any blessing or anything beautiful. Allah can make him live until his death unable to love or be loved or experience the pleasure of friendship and sincerity. In addition to these spiritual torments, Allah can give people relentless diseases, as He points out in this verse, warning about His torment:
Say: "He possesses the power to send you punishment from above your heads or from beneath your feet, or to confuse you in sects and make you taste one another's violence." Look how We vary the signs so that hopefully they will understand. (Surat al-An'am : 65)
People should fear all these possibilities and avoid them by directing themselves towards sincerity without delay.
The time they are given should not deceive people either. Because of His compassion, forgiveness and generosity, Allah allows people a certain period to set themselves on the right path. If one does not use this period to his advantage, the outcome may be inescapable torment, as we are told in this verse of the Qur'an, "How many wrongdoing cities I allowed time to and then I seized them. I am their final destination!" (Surat al-Hajj: 48).
A person cannot know when the period granted him will come to an end. Because of this, and because he may die at any moment, he should make a sincere effort to strengthen his faith and improve his morality. Until death, the way is open to everybody to start over, regain faith and deliver themselves to Allah. The way to be saved from insincerity is very simple: People should reconsider the verses of the Qur'an and, in the light of them, their own intentions and not allow insincerity, open or secret, at any point in their lives.