Many schools of Islamic theology expressing different views on aqidah exist. Any religious belief system, or creed, can be considered an example of aqidah. However, this term has taken a significant technical usage in the Islamic theology, denoting those matters over which Muslims hold conviction. It is a branch of Islamic studies describing the beliefs of Islam. </ref>
Aqidah comes from the Semitic root ?-q-d "to tie; knot".  ("Aqidah" used not only as an expression of a school of Islamic theology or belief system, but as another word for "theology" in Islam, as in: "Theology (Aqidah) covers all beliefs and belief systems of Muslims, including sectarian differences and points of contention".)
According to Muslim scholar Cyril Glasse, "systematic statements of belief became necessary, from early [on in the history of] Islam, initially to refute heresies, and later to distinguish points of view and to present them, as the divergences of schools of theology or opinion increased."
The "first" creed written as "a short answer to the pressing heresies of the time" is known as Fiqh Akbar and ascribed to Abu Hanifa. Two well known creeds were the Fiqh Akbar II "representative" of the Ash'ari, and Fiqh Akbar III, "representative" of the Shafi'i. Al-Ghazali also had an aqidah. These creeds were more detailed than those described below.
The six articles of faith or belief (Arkan al-Iman) derived from the Quran and Sunnah, are accepted by all Muslims. While there are differences between Shia and Sunni Islam and other different schools or sects concerning issues such as the attributes of God or about the purpose of angels, the six articles are not disputed.
The six Sunni articles of belief are:
The first five are based on several Qur?anic creeds:
The sixth point made it into the creed because of the first theological controversy in Islam. Although not connected with the Sunni-Shi?i controversy about the succession, the majority of Twelver Shi?ites do not stress God's limitless power (qadar), but rather His boundless justice (?adl) as the sixth point of belief - this does not mean that Sunnis deny His justice, or Shi?ites negate His power, just that the emphasis is different.
In Sunni and Shia view, having Iman literally means having belief in the six articles.
Tawhid ("doctrine of Oneness") is the concept of monotheism in Islam. It is the religion's most fundamental concept and holds that God (Allah) is one (a?ad) and unique (wid), and the only worthy of worship comparable to Jewish and Christian view on God, while worshipping something else is considered idolatry.
According to Islamic belief, Allah is the proper name of God, and humble submission to his will, divine ordinances and commandments is the pivot of the Muslim faith. "He is the only God, creator of the universe, and the judge of humankind." "He is unique (wid) and inherently one (a?ad), all-merciful and omnipotent." The Qur'an declares the reality of Allah, His inaccessible mystery, His 99 descriptive names expressing a quality characteristic, and His actions on behalf of His creatures.
The Hadith of Gabriel includes the Five Pillars of Islam (Tawhid, Salat, Sawm, Zakat, Hajj) in answer to the question, "O messenger of God, what is Islam?" This hadith is sometimes called the "truly first and most fundamental creed."
Salat is the practice of formal worship in Islam. Its importance for Muslims is indicated by its status as one of the Five Pillars of Islam, with a few dispensations for those for whom it would be difficult. People who find it physically difficult can perform Salat in a way suitable for them. To perform valid Salat, Muslims must be in a state of ritual purity, which is mainly achieved by ritual ablution, (wu), according to prescribed procedures.
In the terminology of Islamic law, sawm means to abstain from eating, drinking (including water) and sexual intercourse from dawn until dusk. The observance of sawm during the holy month of Ramadan is one of the Five Pillars of Islam, but is not confined to that month.
Zakat is the practice of charitable giving by Muslims based on accumulated wealth and is obligatory for all who are able to do so. It is considered to be a personal responsibility for Muslims to ease economic hardship for others and eliminate inequality.
The Hajj is an Islamic pilgrimage to Mecca and the largest gathering of Muslims in the world every year. It is one of the five pillars of Islam, and a religious duty which must be carried out by every able-bodied Muslim who can afford to do so at least once in his or her lifetime.
In addition, some Muslims include Jihad and Dawah as part of aqidah
Jihad (to struggle) and literally means to endeavor, strive, labor to apply oneself, to concentrate, to work hard, to accomplish. It could be used to refer to those who physically, mentally or economically serve in the way of God.
Da'wah ("invitation") means the proselytizing or preaching of Islam. Da'wah literally means "issuing a summon" or "making an invitation," being an active participle of a verb meaning variously "to summon" or "to invite." A Muslim who practices da'wah, either as a religious worker or in a volunteer community effort, is called a d?'? (? plural du'?h, gen: du'?t ?).
A d?'? is thus a person who invites people to understand Islam through dialogue, not unlike the Islamic equivalent of a missionary inviting people to the faith, prayer and manner of Islamic life.
Eschatology is literally understood as the last things or ultimate things and in Muslim theology, eschatology refers to the end of this world and what will happen in the next world or hereafter. Eschatology covers the death of human beings, their souls after their bodily death, the total destruction of this world, the resurrection of humans, the Last Judgment of human deeds by God after the resurrection, and the rewards and punishments for the believers and non-believers respectively. The places for the believers in the hereafter are known as Paradise and for the non-believers as Hell.
Muslim theology is the theology and interpretation of creed (aqidah) that derived from the Qur'an and Hadith. The contents of Muslim theology can be divided into theology proper such as theodicy, eschatology, anthropology, apophatic theology, and comparative religion. In the history of Muslim theology, there have been theological schools among Muslims displaying both similarities and differences with each other in regard to beliefs.
Kal?m is "Islamic scholastic theology" of seeking theological principles through dialectic. In Arabic, the word literally means "speech/words." A scholar of kal?m is referred to as a mutakallim (Muslim theologian; plural mutakallim?n). There are many schools of Kalam, the main ones being the Ash'ari and Maturidi schools in Sunni Islam. Traditionalist theology rejects the use of kalam, regarding humans reason as sinfull in religious matters.
Asharism accepts reason in regard of exegetical matters and traditionalistic ideas. What God does or commands -- as revealed in the Quran and ahadith -- is by definition just. What He prohibits is by definition unjust. Right and wrong are objective realities. The Quran is the uncreated word of God in essence, however it is created then it takes on a form in letters or sound.
Maturidism holds, that humans are creatures endowed with reason, that differentiates them from animals. Further, The relationship between people and God differs from that of nature and God; humans are endowed with free-will, but due to God's sovereignty, God creates the acts the humans choose, so humans can perform them. Ethics can be understood just by reason and do not need prophetic guidances. Maturidi also considered hadiths as unreliable, when they are in odd with reason. However, the human mind alone could not grasp the entire truth, thus it is in need of revelation in regard of mysterious affairs. Further, Maturidism opposes anthropomorphism and similtute, while simultaneously does not deny the divine attributes. They must be either interpreted in the light of Tauhid or be left out.
For the Traditionalist theology, the literal meaning of the Qur'an and especially the prophetic traditions have sole authority in matters of belief, as well as law, and to engage in rational disputation, even if one arrives at the truth, is absolutely forbidden. Atharis engage in an amodal reading of the Qur'an, as opposed to one engaged in Ta'wil (metaphorical interpretation). They do not attempt to rationally conceptualize the meanings of the Qur'an and believe that the real meanings should be consigned to God alone (tafwid). This theology was taken from exegesis of the Quran and statements of the early Muslims and later codified by a number of scholars including Ahmad ibn Hanbal and Ibn Qudamah.
Shi?i Muslims hold that there are five articles of belief. Similar to the Sunnis, the Shi?is do not believe in complete predestination, or complete free will. They believe that in human life there is both free will and predestination.
The branch of Islam known as Isma'ilism is the second largest Shi?i community. They observe the following extra pillars:
Many Muslim scholars have attempted to explain Islamic creed in general, or specific aspects of aqidah. The following list contains some of the most well-known literature.
"Safeguards of Transmission" by Ubayd All?h ibn Mas?d ibn Mahmud ibn Ahmad al-Mahb?b? (died 1346).