Does Īmān Increase & Decrease?

According to the Aḥnāf, the Jamhūr Mutakallimūn, and Imām al-Ḥaramayn al-Shāfiʿī, īmān neither increases nor decreases.

Imām al-Shāfiʿī, Imām Aḥmad, Imām Mālik, the muḥaddithīn, the Jamhūr Ashāʿirah and the Ẓāhiriyyah, by contrast, hold that īmān does increase and decrease. On their view īmān is murakkab, having parts; the more parts a believer holds, the greater his īmān.

A view attributed to Imām Mālik holds that īmān increases but does not decrease, and ʿAllāmah al-Zabīdī attributes the same view to Imām Abū Ḥanīfah. The position is supported by the ẓāhir alfāẓ (apparent wording) of the Qurʾān:

The aḥādīth tell a similar story: there is mention of an increase in īmān, but not of a decrease. Ibn Taymiyyah notes that the aḥādīth speak only of an increase, never of a decrease, with one exception: the ḥadīth in which the Prophet ﷺ describes women as nāqiṣāt al-dīn (lacking in dīn). Even there, the word used is dīn, not īmān; and dīn in this context can also be read as ʿamal, leaving the matter open to interpretation.

In their reading of the relevant āyāt, the Aḥnāf hold that īmān itself does not increase; what increases is its quality. Allāh says:

Whenever Allāh opens a person's heart, that person is granted nūr (light) from his Lord, the nūr of īmān.

Consider Person A, who fulfils all farāʾiḍ and wājibāt and refrains from sin, and Person B, who does not. In terms of the ḥaqīqah of īmān the two are equal: both possess īmān. The effects of īmān, however, the nūr in each, differ.

Shāh Walī Allāh holds that īmān is of two kinds:

1. Mujmal: to believe in all the teachings of the Prophet ﷺ.
2. Mufaṣṣal: to bring īmān on the tafṣīlāt (details) as one comes to learn them.

The increase in īmān mentioned in the Qurʾān, on this reading, refers to īmān mufaṣṣal rather than īmān mujmal: īmān mujmal does not decrease, while īmān mufaṣṣal both increases and decreases.

Take a worked example. Person A knows a hundred teachings of the Prophet ﷺ and believes in all of them; Person B knows two hundred and believes in all of them. It may appear that Person B believes more, but in truth Person B has simply brought īmān over a greater number of details, because he has come to know more.

Someone once put it to Imām Abū Ḥanīfah that he denied an increase in īmān despite the Qurʾānic verses to that effect. He replied:

The ṣaḥābah, may Allāh be pleased with them, believed first; as further teachings were revealed they believed in more. Their increase in īmān was therefore in the details, not in the māhiyyah of īmān.