According to the Ahnaf, Jamhoor Mutakalimeen, Imam al-Haramayn al-Shafiee Iman does not increase or decrease.
On the other hand, Imam Shafi, Imam Ahmad, Imam Malik, the muhaditheen, Jamhoor Asha’ira and Zahiriyya say Iman increases and decreases. They hold the view that iman in murakkab (has parts), so the more parts one has the more their iman increases.
There is one view attributed to Imam Malik which is that Iman increases but does not decrease. Allamah Zabeedi has attributed this sort of opinion to Imam Abu Hanifa as well. This opinion is supported by the zahir alfaz (apparent wording) of the Quran:
وَإِذَا تُلِيَتْ عَلَيْهِمْ آيَاتُهُ زَادَتْهُمْ إِيمَانًا وَعَلَىٰ رَبِّهِمْ يَتَوَكَّلُونَ
And when His verses are recited to them, it increases them in faith; and upon their Lord they rely. Quran 8:2
هُوَ الَّذِي أَنزَلَ السَّكِينَةَ فِي قُلُوبِ الْمُؤْمِنِينَ لِيَزْدَادُوا إِيمَانًا مَّعَ إِيمَانِهِمْ
It is He who sent down tranquillity into the hearts of the believers that they would increase in faith along with their [present] faith. Quran 48:4
وَإِذَا مَا أُنزِلَتْ سُورَةٌ فَمِنْهُم مَّن يَقُولُ أَيُّكُمْ زَادَتْهُ هَٰذِهِ إِيمَانًا ۚ فَأَمَّا الَّذِينَ آمَنُوا فَزَادَتْهُمْ إِيمَانًا وَهُمْ يَسْتَبْشِرُونَ
And whenever a surah is revealed, there are among the hypocrites those who say, “Which of you has this increased faith?” As for those who believed, it has increased them in faith, while they are rejoicing. Quran 9:124
It is a similar case with the ahadith, that mention of an increase in Iman is found, but not that of a decrease. Ibn Taymiyyah says that in the ahadith there is only mention of an increase in Iman and not of a decrease in Iman except for one hadith, This is the hadith where the Prophet (saw) mentions that women are naaqisat of deen (lacking in deen). Even in this hadith the word “deen” is used as opposed to Iman. In this case, the word “deen” could also be considered to mean amal, therefore it is debatable and not clear cut.
In interpreting the ayat, the Ahnaf say that actual Iman does not increase, but rather its quality increases. Allah says:
أَفَمَن شَرَحَ اللَّهُ صَدْرَهُ لِلْإِسْلَامِ فَهُوَ عَلَىٰ نُورٍ مِّن رَّبِّهِ
So is one whose breast Allah has expanded to [accept] Islam and he is upon a light from his Lord [like one whose heart rejects it]? Quran 39:22
Whenever Allah opens ones heart, they are given noor (light) from their lord i.e. the noor of Iman
For example, Person A fulfils all faraaid and waajibaat and stays away from sins. Person B does not fulfil all his faraaid and waajibaat. In terms of haqeeqat of Iman, these two are equal, they both have Iman. However the effects of Iman, the noor is different.
Shah Waliullah says Iman is of two types:
- Mujmal – to believe in all the teachings of the prophet
- Mufassal – to bring Iman on the tafseelat (details) as you learn more
Therefore it can be thought that the increase in Iman mentioned in the Quran refers to that of Iman Mujmal. i.e. Iman Mujmal does not decrease, Iman Mufassal does increase & decrease
For example person A knows 100 teachings of the prophet and believes in all. Person B knows 200 teachings of the Prophet and believes in all. It may seem as though Person B believes more but the reality is that Person B has brought Iman on more things as he knows more.
Someone asked Imam Abu Hanifa that you deny the increase in Iman even though it is mentioned in the Quran. He replied:
أمنوا بالإجمال ثم بالتفصيل
The sahaba, may Allah be pleased with them believed, then as teachings were revealed believed in more. Therefore their increase in Iman was in the details not in the maahiyat of Iman.
