The Difference between 'Islam' and 'Iman'

Do the terms Iman and Islam ever mean the same thing? Or do their meanings always differ?
When the terms Islam and Iman are mentioned in the same verse or hadeeth their meaning differs. When mentioned separately they mean one and the same. Understanding this aspect of our `aqeedah can help us better understand texts of the Qur'aan and Sunnah. Here is how:

The terms Islam and Iman were precisely defined in the hadeeth of Jibreel `alayhis salaam by the pillars they comprise. This famous hadeeth narrated by Muslim explains that Islam is to testify that there is nothing worthy of worship except Allaah, and that Muhammad (sallallaahu `alayhi wa `alaa aalihi wa sallam) is the Messenger of Allaah, to perform prayer, to give the zakaat, to fast the month of Ramadhaan and to perform Hajj, if one has the means to do so. Iman, on the other hand, is to believe in Allaah, and His Angels, and His Books and His Messengers, and in the Last Day, and the qadar (divine pre-ordainment), good and evil consequences thereof.

More generally, one could say that Iman is construed to mean testifying and belief, while Islam represents external submission, such as affirmation by tongue and action by limbs. Whoever has faith, he has Islam, and whoever has Islam, he has some degree of faith. This is the reason why when one of these two terms is mentioned, the other is taken for granted and is included in it. When it is said in the Qur’aan, "Verily the Deen with Allaah is Islam." [3:17] or "Whoever seeks religion other than Islam it will never be accepted from him." [3:85], the meaning of Faith is included in the term Islam. There cannot be Islam without any faith and it cannot be that Allaah accepts Islam with no Iman at all. So when one is mentioned, the other one is included.

Also, one cannot have Iman without Islam. An evidence from the Qur’aan that Iman is of higher degree than Islam and that when both are mentioned together, they mean two different things is the verse in Soorat ul-Hujuraat: "The bedouins say: ‘We believe.’ Say: ‘You believe not but you only say: ‘We have surrendered (in Islam).’" [49:14] One cannot claim for himself a high level of faith and a strong commitment to Islam in accordance with the descriptions of true believers in the Qur’aan and Sunnah.

The Iman that is negated in the above verse is the complete Iman, or what some scholars, such as Ibn Taymeeyah in Al-`Aqeedat ul-Wasitiyyah, termed "al-Iman al-Mutlaq" [Absolute Iman], which could be defined as Iman that does not lack in any of its roots and branches, its internal or external aspects, and an Iman that is proven in the heart, on the tongue and with the limbs. Those who are Muslims, but their Iman al-Mutlaq is negated still have Iman, however their Iman is deficient.

Therefore the term Islam still includes the meaning of both Islam and Iman. Another example where the absolute Iman is negated is the hadeeth: "When an adulterer commits illegal sexual intercourse, then he is not a believer at the time he is doing it, and when a drinker of an alcoholic liquor drinks it, and when a thief steals, then he is not a believer at the time of stealing, and when a robber robs, and the people look at him, then he is not a believer at the time of doing robbery. [al-Bukhaaree] Therefore, when Islam is mentioned without Iman, it includes Iman - as action without faith is hypocrisy - but it does not necessarily include al-Iman al-Mutlaq.

The Qur’anic descriptions of those who are mu’minoon [as in the beginning of soorat ul-mu’minoon] necessarly include the meaning of muslimoon. Those who are Muslims necessarily have some degree of faith, and Islam that Allaah (subhaanahu wa ta`aalaa) accepts also necessarily includes Iman, as for instance in the hadeeth that mentions the questioning in the grave: "…They continue, ‘What is your religion?’ He [believer] answers: ‘Islam is my religion.’" [from an authentic hadeeth mentioned by al-Albaanee in Ahkaam ul-Janaa’iz] The term ‘Islam’ here necessarily includes the meaning of Iman as well. And the following hadeeth includes both the meaning of Iman and Islam: "The best believers according to their Iman are those with the best character." [At-Tabaraanee, Saheeh Jaami` us-Sagheer #1129]