Sunni Islam is the largest branch of Islam, and the oldest group of Muslims. Sunni Muslims are referred to in Arabic as Ahl ūs-Sunnah wa āl-Jamāah (Arabic: أهل السنة والجماعة‎), "people of the tradition of Muhammad and the consensus of the Ummah" or Ahl ûs-Sunnah (Arabic: أهل السنة‎) for short; in English, they are known as Sunni Muslims, Sunnis or Sunnites.

Sunni Islam is sometimes referred to as the orthodox version of the religion. The word "Sunni" comes from the term Sunnah (Arabic: سنة‎), which refers to the sayings and actions of Muhammad that are recorded in hadiths (collections of narrations regarding Muhammad).

The primary hadiths Al-Kutub Al-Sittah, in conjunction with the Quran, form the basis of all jurisprudence methodologies within Sunni Islam. Laws are derived from the text of the Quran and the hadith, in addition to using methods of juristic reasoning (like qiyas) and consensus (ijma). There is a multitude of scholarly opinions in each field; however, these can be summarised as either derived from the four major schools of thought (Madh'hab) or from an expert scholar who exercises independent derivation of Islamic Law (ijtihad). Both are considered valid as differences of opinion were present at the time of the early Muslims (the Salaf).

Shia Islam (Arabic: شيعة‎, Shîah) is the second largest denomination of Islam. Adherents of Shia Islam are called Shi'is [shç-çz], Shi'ites, or Shias. "Shia" is the short form of the historic phrase Shîatu Alî (شيعة علي), meaning "followers of Ali", "faction of Ali", or "party of Ali".

Like other schools of thought in Islam, Shia Islam is based on the teachings of the Quran and the message of the Islamic prophet Muhammad. In contrast to other schools of thought, the Shia believe that only God has the right to choose a representative to safeguard Islam, the Quran and sharia (based upon verses in the Quran which stipulate this according to the Shia). For this reason, the Shias look to Ali, whom they consider divinely appointed, as the rightful successor to Muhammad, and the first imam. The Shia believe that there are numerous narrations where Muhammad selected Ali as his successor.

Shias believe that Muhammad's family, the Ahl al-Bayt ("the People of the House"), and certain individuals among his descendants, who are known as Imams, have special spiritual and political authority over the community. Therefore, Shias prefer hadith attributed to the Ahl al-Bayt and close associates, and have their own separate collection of hadiths. All Shias agree on the succession of Hassan and Hussein after Ali, but they may differ after Hussein. Hassan and Hussein are described by Shias as "leaders of all youths in Paradise", and believe that these sons of Ali were the true leaders and caliphs of the Muslims. Shias regard Ali as the successor of Muhammad not only ruling over the community in justice, but also interpreting Islamic practices and its esoteric meaning. Hence he was regarded as being free from error and sin (infallible), and appointed by God by divine decree (nass) to be the first Imam. Ali is known as "perfect man" (al-insan al-kamil) similar to Muhammad, according to Shia viewpoint.

Wahhabism (Arabic: وهابية‎) is an ultra-conservative branch of Islam. It is a form of Salafism, and a religious movement within Sunni Islam. Wahhabism was developed by an eighteenth century Muslim theologian, Muhammad ibn Abd al-Wahhab (1703–1792) from Najd, Saudi Arabia. Ibn Abd Al-Wahhab advocated purging Islam of what he considered to be impurities and innovations. His has become the dominant form of Islam in Saudi Arabia. Its adherents prefer to be referred to as Salafis.

The movement claims to adhere to the correct understanding of the general Islamic doctrine of Tawhid, on the "uniqueness" and "unity" of God, shared by the majority of Islamic sects, but uniquely interpreted by Ibn Abd Al-Wahhab. Ibn Abd-al-Wahhab was influenced by the writings of Ibn Taymiyya and questioned classical interpretations of Islam, claiming to rely on the Qur'an and the Hadith. He attacked a "perceived moral decline and political weakness" in the Arabian Peninsula and condemned what he perceived as idolatry, the popular cult of saints, and shrine and tomb visitation.

The Wahhabi teachings disapprove of veneration of the historical sites associated with early Islam, on the grounds that only God should be worshipped and that veneration of sites associated with mortals leads to idolatry. Many buildings associated with early Islam, including mazaar, mausoleums and other artifacts have been destroyed in Saudi Arabia by Wahhabis from early 19th century through the present day. This practice has proved controversial and has received considerable criticism from Sunni and Shia Muslims and in the non-Muslim World.

The first ones to oppose this new trend within Islam, as introduced by Muhammad Ibn Abd al-Wahhab, were his father Abd al-Wahhab, his brother Salman Ibn Abd al-Wahhab, who was an Islamic scholar, and a qadi, who wrote a book in refutation of his brothers' new teachings, called: "The Final Word from the Qur'an, the Hadith, and the Sayings of the Scholars Concerning the School of Ibn `Abd al-Wahhab"), also known as: "Al-Sawa`iq al-Ilahiyya fi Madhhab al-Wahhabiyya" ("The Divine Thunderbolts Concerning the Wahhabi School"). In "The Refutation of Wahhabism in Arabic Sources, 1745–1932", Hamadi Redissi provides original references to the description of Wahhabis as a divisive sect (firqa) and outliers (Kharijites) in communications between Ottomans and Egyptian Khedive Muhammad Ali. Redissi details refutations of Wahhabis by scholars (muftis); among them Ahmed Barakat Tandatawin, who in 1743 describes Wahhabism as ignorance (Jahala).

In 1801 and 1802, the Saudi Wahhabis under Abdul Aziz ibn Muhammad ibn Saud attacked and captured the holy Muslim cities of Karbala and Najaf in Iraq, massacred parts of the Muslim population and destroyed the tombs of Husayn ibn Ali, the grandson of Muhammad, and son of Ali (Ali bin Abu Talib), the son-in-law of Muhammad. In 1803 and 1804 the Saudis captured Makkah and Medina and destroyed historical monuments and various holy Muslim sites and shrines, such as the shrine built over the tomb of Fatimah, the daughter of Muhammad, and even intended to destroy the grave of Muhammad himself as idolatrous. In 1998 the Saudis bulldozed and poured gasoline over the grave of Aminah bint Wahb, the mother of Muhammad, causing resentment throughout the Muslim World.

A study conducted by the NGO Freedom House found Wahhabi publications in mosques in the United States. These publications included statements that Muslims should not only "always oppose" infidels "in every way", but "hate them for their religion … for Allah's sake", that democracy "is responsible for all the horrible wars of the 20th century", and that Shia and certain Sunni Muslims were infidels.

The Saudi government issued a response to this report, stating: "It has worked diligently during the last five years to overhaul its education system but overhauling an educational system is a massive undertaking".
A review of the study by Institute for Social Policy and Understanding (ISPU) complained the study cited documents from only a few mosques, arguing most mosques in the U.S. are not under Wahhabi influence. ISPU comments on the study were not entirely negative however, and concluded:

American-Muslim leaders must thoroughly scrutinize this study. Despite its limitations, the study highlights an ugly undercurrent in modern Islamic discourse that American-Muslims must openly confront. However, in the vigor to expose strains of extremism, we must not forget that open discussion is the best tool to debunk the extremist literature rather than a suppression of First Amendment rights guaranteed by the U.S. Constitution.

Khaled Abou El Fadl attributed the appeal of Wahhabism to some Muslims as stemming from:

Arab nationalism, which followed the Wahhabi attack on the Ottoman Empire;
Reformism, which followed a return to Salaf (as-Salaf aṣ-Ṣâliḥ;)
Destruction of the Hejaaz Khilafa in 1925;
Control of Mecca and Medina, which gave Wahhabis great influence on Muslim culture and thinking;
Oil, which after 1975 allowed Wahhabis to promote their interpretations of Islam using billions from oil export revenue.

The Wahhabi subscribe to the primary doctrine of the uniqueness and unity of God (Tawhid). The first aspect is believing in God's Lordship that He alone is the believer's lord (Rabb) The second aspect is that once one affirms the existence of God and His Lordship, one must worship Him and Him alone.

Wahhabi theology treats the Quran and Hadith as the only fundamental and authoritative texts. Commentaries and "the examples of the early Muslim community (Ummah) and the four Rightly Guided Caliphs (AD 632-661)" are used to support these texts, but are not considered independently authoritative.

Ibn Abd al-Wahhab further explains in his book Kitab al-Tawhid (which draws on material from the Quran and the narrations of the prophet) that worship in Islam includes conventional acts of worship such as the five daily prayers; fasting; Dua (supplication); Istia'dha (seeking protection or refuge); Ist'ana (seeking help), and Istigatha (seeking benefits). Therefore, making dua to anyone or anything other than God, or seeking supernatural help and protection that is only befitting of a divine being from something other than Allah are acts of "shirk" and contradict Tawhid. Ibn Abd al-Wahhab further explains that Muhammad during his lifetime tried his utmost to identify and repudiate all actions that violated these principles.

The most important of these commentaries are those by Ibn Abd al-Wahhab in particular his book Kitab al-Tawhid, and the works of Ibn Taymiyyah. Ibn Abd al-Wahhab was a follower of Ahmad ibn Hanbal's school of fiqh (Islamic jurisprudence) like most in Nejd at the time, but "was opposed to any of the schools (Madh'hab) being taken as an absolute and unquestioned authority". Therefore, he condemned taqlid, or blind adherence, at the scholarly level. Although Wahhabis are associated with the Hanbali school, early disputes did not center on fiqh and the belief that Wahhabism was borne of Hanbali thought has been called a "myth".

I. FUNDAMENTAL ARTICLES OF FAITH

A. GOD...
1. Islam "is predicated on the belief that there is but one God,
Allah, the Creator of the universe and of humankind...Mercy and
compassion are his principal qualities."
-- Introduction To Islam, M. Cherif Bassiouni
2. "The first and most essential element in Islamic theology is
the doctrine of God (Allah)."
a. "True belief demands an uncompromising monotheism."
b. Muhammad "accused Christians of being polytheists because of
their belief in the Trinity"
-- Solomon Nigosian, Islam: The Way Of Submission
3. Thus they view Jesus as simply a prophet, not the Son of God
- cf. Qur'an 4:171; 5:73,75

B. ANGELS...
1. "Angels are frequently mentioned in the Qur'an."
2. "They are God's messengers who exercise a potent influence on
both the life of humans and the life of the universe."
3. "...angels are said to act as intermediaries asking God to
forgive the offenses of believers" - Qur'an 40:7
4. "At the time of death, the souls of humans are received by
angels (Qur'an 6:93; 8:52; 16:30; 47:29), who have kept a
record of their actions (Qur'an 6:61; 43:80; 82:10) and will
witness for or against them on the Day of Judgment (Qur'an
21:103; 13:24; 33:43)"

C. BOOKS (SCRIPTURES)...
1. "One of the central doctrines of Islamic faith is belief in all
of God's revealed messages, which now consist of four books:
Torah, Psalms, Gospels, and Qur'an."
2. "These four Books are to be regarded as Holy Scriptures, even
though the three Books preceding the Qur'an include certain
human imperfections."
3. "With the appearance of the Qur'an, the noblest of the Books,
these earlier Books, it is believed, were abrogated."
4. "...it is an article of faith that the purpose of the Qur'an is
to preserve original divine revelations by restoring the
eternal truth of God." (Qur'an 5:44-48)
5. "Since the Qur'an abrogates all earlier Books, its ordinances
continue to remain in force until the Day of Judgment..."

D. PROPHETS (MESSENGERS)...
1. "To all peoples and in all ages, God sent prophets or
messengers to proclaim the Oneness of God and to warn humanity
of the future judgment (Qur'an 10:47; 16:36)."
2. The Qur'an mentions many by name: - cf. Qur'an 6:83-90
a. Most are Old Testament figures (Adam, Enoch, Noah, Lot,
Abraham, Ishmael, Isaac, Jacob, Joseph, Moses, Aaron,
Elijah, Elisha, David, Solomon, Job, Jonah, Ezra)
b. Three are from the New Testament (Zacharias, John, Jesus)
3. "Just as Adam is regarded by Muslims as the first prophet sent
by God, so Muhammad is the 'seal of the prophets' through whom
God reveals His eternal message in its definitive form (Qur'an
33:40)."
4. "Muhammad's life and death marked the end of prophecy since his
prophetic mission satisfied for all time any need or demand for
another prophet."

E. THE DAY OF JUDGMENT...
1. "The Last Day, or the final Day of Judgment, occupies a very
important place in Qur'an and in the Hadith."
2. "The vivid description of the events leading up to the Last Day
and the elaborate portrayal of the final judgment are very
similar to the book of Revelation..." - cf. Qur'an 81:1-14;
82:1-19; 69:13-37
3. "...Islamic doctrine associates the coming of 'The Guided One'
(Mahdi) with signs that foreshadow the Last Day."
a. "Some Sunni Muslims believe that an individual from the
family of the Prophet Muhammad will appear and reign for
seven years to make the religion of Islam triumphant
throughout the world before the end comes."
b. "Most Sunni scholars, however, identify this Messianic
figure with the prophet Jesus."
4. "...Muslims believe that on the Last Day, the graves will be
open, the dead will resurrect, and a judgment will be
pronounced on every individual according to his or her deeds."

[Taking a look now at some of the religious practices of those who are
Muslims, Islam is perhaps most noted for what is called...]

II. THE FIVE PILLARS (RELIGIOUS DUTIES)

A. THE CREED OF ISLAM (SHEHADA)...
1. This is the profession of faith in Islam: "There is no other
god but God; and Muhammad is the Prophet of God" (la ilaha
ill'Allah, Muhammad rasul Allah)
2. Professing this creed is sufficient to make one a convert to
Islam, provided the following conditions are met:
a. To repeat it aloud
b. To understand it perfectly
c. To believe it in the heart
d. To profess it till death
e. To recite it correctly
f. To declare it without hesitation

B. PRAYERS (SALAT)...
1. "The next most important religious duty after the profession of
faith is prayer."
2. "Qur'anic texts prescribe only three prayers a day, but Islamic
tradition requires five: at dawn, noon, mid-afternoon,
evening, and night."
3. "Muslims may not waive the obligation to pray five times daily
even if they are sick or on a journey."
a. "The sick are to pray in bed and, if necessary, lying down."
b. "Travelers are enjoined to pray at dawn, to combine noon
with mid-afternoon prayer, and evening prayer with prayers
that follow nightfall, thus praying three times daily."
4. "Prayers may be said either in private or in public worship."
5. "All public or ritual prayers must be preceded by ritual
purification both of the individual and the place. Ablutions
(wudu' or ghusl) secure bodily purity."
a. "...Muslims was their foreheads, hands, and feet before they
pray..."
b. "If no water is available, then hands and feet may be wiped
with fine, clean sand."
c. "Muslims pray on a mat or rug in token of purity secured for
the spot or place."
d. "Shoes or sandals are removed before devotees step on their
prayer rugs."
6. "...a worshipper prays facing in the direction of Mecca (qibla)
a direction which is indicated in mosques by a niche in the
wall (mihrab)."
7. "One day a week is set aside as a day of public prayer (Friday)
...Muslim women do not attend public prayers, although some
mosques have a room or section set aside for them."
8. "Prayer is the heart and essence of Islam. Any Muslim who
willfully avoids prayer is considered to have forsaken Islam."


C. RELIGIOUS TAX (ZAKAT)...
1. "The third duties of a Muslim is to give alms to the poor as an
outward sign of true piety."
2. "There are two kinds of almsgiving: legal (zakat) and voluntary
(sadaqa)."
3. "In Muslim canon law legal alms are assessed at one-fortieth
(2.5%) of an individual's income in kind or money."
4. "Legal almsgiving is now more or less defunct, because many
Muslim states follow western systems of taxation."


D. FASTING (SIYAM)...
1. "The fourth duty of a Muslim is to fast during the twenty-nine
days of the ninth month of the Islamic lunar calendar (the
month of Ramadan)."
2. "...during the day Muslims abstain from food, drink, and sexual
intercourse; but these proscriptions are lifted between sunset
and sunrise."
a. "All adult male and female Muslims fast from sunrise to
sunset."
b. "Only children, the sick, nursing or pregnant mothers, the
aged and travelers are exempt, though anyone exempted by
reason of temporary disability or circumstances is expected
to make up an equivalent period of fasting."
c. "The end of each daytime abstention is celebrated joyfully
after sunset."
3. "Those who observe the fast faithfully and in a spirit of
sincere repentance are assured of a remission of sins."
a. "Voluntary fasts at various times during the year other than
the month of Ramadan are also considered as meritorious
acts..."
b. "None, however, other than Ramadan, may last any more than
three consecutive days."


E. PILGRIMAGE (HAJJ)...
1. "The fifth prescribed religious duty of every Muslim is to make
a pilgrimage to the holy shrine of Ka'ba in Mecca."
2. "It is an obligation to be fulfilled at least once in a
lifetime by every adult who is sane, healthy, financially
capable of supporting his family during his absence, and able
to underwrite the expenses of the journey."
3. "The pilgrimage...can be performed only on specified days (the
seventh to the tenth) in the last month (Dhu'l Hijja, the
twelfth month) of the Islamic calendar."
4. "A cross-section of Muslims from all walks of life and of
varying color, race and nationality realize their equality
before God as they meet on common ground at least once a year."