Iman (Arabic: الإيمان) in Islamic theology denotes a believer's faith in the metaphysical aspects of Islam. Its most simple definition is the belief in the six articles of faith, known as arkān al-īmān.
The term Iman has been delineated in both the Quran as well as the famous Hadith of Gabriel. According to the Quran, Iman must be accompanied by righteous deeds and the two together are necessary for entry into Paradise. In the Hadith of Gabriel, Iman in addition to Islam and Ihsan form the three dimensions of the Islamic religion.
There exists a debate both within and outside Islam on the link between faith and reason in religion, and the relative importance of either. Several scholars contend that faith and reason spring from the same source and hence must be harmonious.
In the Arabic language, Iman denotes faith or certitude to the unseen.
Iman can be stated as acknowledging God with full sincerity of heart whilst accepting all His attributes and their obvious corollaries. Farāhī, whilst explaining the meaning of Imān in his exegesis, has written:
"The root of imān is amn. It is used in various shades of meaning. One of its derivatives is mu’min, which is amongst the noble names of Allah because He gives peace to those who seek His refuge. This word is also an ancient religious term. Hence the certitude which exists with humility, trust and all the conditions and corollaries of adherence to a view is called imān and he who professes faith in Allah, in His signs and in His directives and submits himself to Him and is pleased with all His decisions is a mu’min."
The Six articles of Islamic faith
Iman is generally outlined using the six articles of faith:
- Belief in God
- Belief in the Angels
- Belief in Divine Books
- Belief in the Prophets
- Belief in the Day of Judgment
- Belief in God's predestination
Of these, the first five are mentioned together in the Qur'an  and Prophet Muhammad, while including a corollary of belief in Allah – the good and evil of fate ordained by God – has referred to all six together in the following manner in the Hadith of Gabriel:
"Iman is that you believe in God and His Angels and His Books and His Messengers and the Hereafter and the good and evil fate [ordained by your God]." 
Another similar narration ascribed to the Prophet is:
Ibn Abbas narrates that the Angel Jibril once asked the Prophet: "Tell me what is Iman?" The Prophet replied: "Iman is to believe in Allah, the Day of Judgment, His (Allah's) Angels, Books and Prophets and to believe in life after death; and to believe in Paradise and the Fire, and the setting up of the Mizan (scales) to weigh the deeds; and to believe in the Divine Decree, the good and the bad of it (all). Jibril then asked him: "If I do all this will I be with Iman?" The Prophet said: "When you have done all of this, you will be having Iman." 
It is also assumed that the essential Iman consists of the first 3 items (Belief in God, Prophets, and the Hereafter).
Delineation in the Quran and Hadith
In the Quran, Iman is one of the 10 qualities which cause one to be the recipient of God's mercy and reward. The Quran states that faith can grow with remembrance of God. The Qur'an also states that nothing in this world should be dearer to a true believer than faith.
Prophet Muhammad is reported to have said that he gained sweetness of faith who was pleased to accept God as Lord, Islam as religion and Muhammad as prophet. He also said that no one can be a true believer unless he loves the Prophet more than his children, parents and relatives. At another instance, he has remarked that it is this love with God and the Prophet after which a person can be aware of the real taste of faith.
… it does not merely imply the passionate love one naturally has for one’s wife, children and other relatives, but it also refers to the love on the basis of intellect and principles for some viewpoint and stance. It is because of this love that a person, in every sphere of life, gives priority to this viewpoint and principle ... So much so, if the demands of his wife, children and relatives clash with the demands of this viewpoint, he adheres to it and without any hesitation turns down the desires of his wife and children and the demands of his family and clan.
Islahi and Maududi both have inferred that the Quranic comparison of a good word and a bad word in Chapter 14 is actually a comparison of faith and disbelief. Thus, the Qur'an is effectively comparing faith to a tree whose roots are deep in the soil and branches spread in the vastness of the sky.
Iman is also the subject of a supplication uttered by the Prophet to God:
O God! I have resigned myself to You and I have consigned my matter to you and have taken support from You fearing Your grandeur and moving towards You in anticipation. There is no refuge and shelter after running away from You, and if there is, it is with You. Lord! I have professed faith in your Book which You have revealed and have professed faith in the Prophet you have sent as a Messenger.
Requirements of Iman
- Righteous Deeds (a'mal-i salih)
- Urging one another to the truth and urging one another to remain steadfast on it (tawasi bi al-haqq wa tawasi bi al-sabr)
Similarly, the contingent requirements of Iman are:
- Migration for the Cause of Religion (Hijrah)
- Helping the Cause of Religion (Nusrah)
- Adhering to Justice (Qiyam bi al-Qist)...
The 77 Branches of Iman
The 77 Branches of Faith is a collection compiled by Imam Al-Bayhaqi in his work Shu`ab al-Iman. In it, he explains the essential virtues that reflect true faith (Iman) through related Qur'anic verses and prophetic sayings. 
This is based on the following Hadith ascribed to Prophet Muhammad:
Abu Hurayrah narrated that the Prophet said: "Iman has more than 70 branches. The most excellent among these branches is the saying of "Laa ilaaha ill Allah" (there is no God but Allah), and the smallest branch is to remove an obstacle from the wayside. And Haya (modesty) is an important branch of Iman." 
Faith and deeds
In Islam, it is essential that there exist harmony and concord between faith and deeds. Farāhī has explained this aspect in his tafsīr in the following manner:
Righteous deeds are mentioned in the Qur’ān right after faith in the capacity of an explanation … In the case of faith, the need for its explanation is obvious: the place of faith is the heart and the intellect. In matters of intellect and heart, not only can a person deceive others but also at times he himself can remain in deception. He considers himself to be a mu’min (believer) whereas actually he is not. For this reason, two testimonies needed to be required for it: a person’s words and a person’s deeds. Since words can be untrue, hence a person who only professes faith through words is not regarded as a mu’min and it was deemed essential that a person’s deeds also testify to his faith. Thus the Qur’ān said: O you who believe with the tongue! Believe through your deeds.
Faith and reason in Islam
The relation between reason and faith in Islam is a complex debate spanning over centuries. Ismail Raji al-Faruqi states on this subject:
As for the non-Muslims, they may contest the principles of Islam. They must know, however, that Islam does not present its principles dogmatically, for those who believe or wish to believe, exclusively. It does so rationally, critically. It comes to us armed with logical and coherent arguments, and expects our acquiescence on rational, and hence necessary, grounds. It is not legitimate for us to disagree on the relativist basis of personal taste, or that of subjective experience.
There are six Kalimas.
These following are associated with Muslim declarations of faith but they are not kalimas:
Iman-e-Mufassil (or the Detailed declaration of faith)
I have faith in Allah and His Angels, His Books and His Messengers, and the Day of Judgment and that all good and evil and fate is from Allah and it is sure that there will be resurrection after death.
Iman-e-Mujmal (or the Summary declaration of faith)
I have faith in Allah as He is known by His Names and attributes and I accept all His commands.
- Farāhī, Majmū‘ah Tafāsīr, 2nd ed. (Faran Foundation, 1998), 347.
- Frederick M. Denny, An Introduction to Islam, 3rd ed., p. 405
- Quran 2:285
- Quran 95:6
- Islahi, Amin Ahsan. Mabadi Tadabbur-i-Hadith (tr: Fundamentals of Hadith Intrepretation)
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- Farāhī, Majmū‘ah Tafāsīr, 2nd ed. (Faran Foundation, 1998), 347.
- Quran 106:4
- Quran 2:285
- Muslim, Al-Jami‘ al-sahih, 22, (no. 93).
- Musnad Ahmad"
- Dr. Israr Ahmad, Haqiqat Iman great
- Quran 33:35
- Quran 8:2
- Quran 9:24
- Muslim, Al-Jami‘ al-sahih, 38, (no. 151).
- Al-Bukhari, Al-Jami‘ al-sahih, 6, (no. 15)
- Muslim, Al-Jami‘ al-sahih, 41, (no. 169)
- Al-Bukhari, Al-Jami‘ al-sahih, 6-7, (nos. 16, 21)
- Muslim, Al-Jami‘ al-sahih, 40, (no. 165)
- Amin Ahsan Islahi, Tazkiyah-i nafs (tr: Self Purification), 119
- Quran 14:24–26
- Amin Ahsan Islahi, Tazkiyah-i nafs, 325.
- Al-Bukhari, Al-Jami‘ al-sahih, 45, (no. 247)
- Ghamidi, Javed Ahmad. Mizan (tr: Islam, A Comprehensive Introduction). Al-Mawrid. 2009
- Quran 103:1–3
- Quran 4:97
- Quran 61:10–14
- Quran 9:24
- Quran 4:135
- Quran 5:8
- Sahih Muslim
- Farāhī, Majmū‘ah Tafāsīr, 2nd ed. (Faran Foundation, 1998), 349.
- Quran 4:136
- Isma'il Raji al Faruqi, Islam and Other Religions