Within the Islamic tradition, tajdid has been an important religious concept, which has manifested itself throughout Islamic history in periodic calls for a renewed commitment to the fundamental principles of Islam and reconstruction of society in accordance with the Quran and the traditions of the Islamic prophet Muhammad (hadith). The concept of tajdid has played a prominent role in contemporary Islamic revival.
In academic literature, "Islamic revival" is an umbrella term encompassing "a wide variety of movements, some intolerant and exclusivist, some pluralistic; some favorable to science, some anti-scientific; some primarily devotional, and some primarily political; some democratic, some authoritarian; some pacific, some violent".
Since the 1970s, a worldwide Islamic revival has emerged, owing in large part to popular disappointment with the secular nation states and Westernized ruling elites, which had dominated the Muslim world during the preceding decades, and which were increasingly seen as authoritarian, ineffective and lacking cultural authenticity. It is also motivated by a desire to "restore Islam to ascendancy in a world that has turned away from God". The revival has been accompanied by growth of various reformist-political movements inspired by Islam (also called Islamist), and by "re-Islamisation" of society from above and below, with manifestations ranging from sharia-based legal reforms to greater piety and growing adoption of Islamic culture (such as increased attendance at Hajj) among the Muslim public. Among immigrants in non-Muslim countries, it includes a feeling of a "growing universalistic Islamic identity" or transnational Islam, brought on by easier communications, media and travel. The revival has also been accompanied by an increased influence of fundamentalist preachers and terrorist attacks carried out by some radical Islamist groups on a global scale.
Preachers and scholars who have been described as revivalists or mujaddideen, by differing sects and groups, in the history of Islam include Ahmad ibn Hanbal, Ibn Taymiyyah, Shah Waliullah, Ahmad Sirhindi, Muhammad ibn Abd-al-Wahhab, and Muhammad Ahmad. In the 20th century, figures such as Hassan al-Banna, Malcolm X, and Ruhollah Khomeini, have been described as such, and academics often use the terms "Islamist" and "Islamic revivalist" interchangeably. Contemporary revivalist currents include Islamic liberalism, which seeks to reconcile Islamic beliefs with modern values; neo-Sufism, which cultivates Muslim spirituality; and neo-fundamentalism, which stresses obedience to Islamic law and ritual observance.
Earlier history of revivalism
Within the Islamic tradition, tajdid (lit., regeneration, renewal) has been an important religious concept. Early on into the Islamic era, Muslims realized that they have not succeeded in creating and maintaining a society that truly followed the principles of their religion. As a result, Islamic history has seen periodic calls for a renewed commitment to the fundamental principles of Islam and reconstruction of society in accordance with the Quran and the traditions of the Islamic prophet Muhammad (hadith). These efforts often drew inspiration from the hadith in which Muhammad states: "God will send to His community at the head of each century those who will renew its faith for it". Throughout Islamic history, Muslims looked to reforming religious leaders to fulfill the role of a mujaddid (lit., renewer). Although there is disagreement over which individuals might actually be identified as such, Muslims agree that mujaddids have been an important force in the history of Islamic societies.
The modern movement of Islamic revival has been compared with earlier efforts of a similar nature: The "oscillat[ion] between periods of strict religious observance and others of devotional laxity" in Islamic history was striking enough for "the Arab historian, Ibn Khaldun to ponder its causes 600 years ago, and speculate that it could be "attributed ... to features of ecology and social organization peculiar to the Middle East", namely the tension between the easy living in the towns and the austere life in the desert.
Some of the more famous revivalists and revival movements include the Almoravid and Almohad dynasties in Maghreb and Spain (1042–1269), Indian Naqshbandi revivalist Ahmad Sirhindi (~1564–1624), the Indian Ahl-i Hadith movement of the 19th century, preachers Ibn Taymiyyah (1263–1328), Shah Waliullah (1702–1762), and Muhammad ibn Abd-al-Wahhab (d. 1792).
In the late 19th century, Jamal-al-Din Afghani, "one of the most influential Muslim reformers" of the era, traveled the Muslim world, advocating for Islamic modernism and pan-Islamism. His sometime acolyte Muhammad Abduh has been called "the most influential figure" of Modernist Salafism. In 1928 Hassan al-Banna established the Muslim Brotherhood, the first mass Islamist organization. Other influential revival activists and thinkers include Rashid Rida and Ali Abdel Raziq.
In South Asia, Islamic revivalist intellectuals and statesmen like Syed Ahmed Khan, Muhammad Iqbal, Muhammad Ali Jinnah promoted the Two-Nation Theory and the Muslim League established the world's first modern Islamic republic, Pakistan. Abul Ala Maududi was the later leader of this movement who established Jamaat-e-Islami in South Asia. Today it is one of the most influential Islamic parties in the Indian sub-continent, spanning three countries (Pakistan, India, and Bangladesh), although the different national parties have no organisational link between them.
Whether or not the contemporary revival is part of an historical cycle, the uniqueness of the close association of the Muslim community with its religion has been noted by scholar Michael Cook who observed that "of all the major cultural domains" the Muslim world "seems to have been the least penetrated by irreligion". In the last few decades ending in 2000, rather than scientific knowledge and secularism edging aside religion, Islamic fundamentalism has "increasingly represented the cutting edge" of Muslim culture.
A global wave of Islamic revivalism emerged starting from 1970s owing in large part to popular disappointment with the secular nation states and Westernized ruling elites, which had dominated the Muslim world during the preceding decades, and which were increasingly seen as authoritarian, ineffective and lacking cultural authenticity. It was also a reaction against Western influences such as individualism, consumerism, commodification of women, and sexual liberty, which were seen as subverting Islamic values and identities. Economic and demographic factors, such as lagging economic development, a rise in income inequality and a decline in social mobility, the rise of an educated youth with expectation of higher upward mobility, and urbanization in the Muslim world also played a major part. In general, the gap between higher expectations and reality among many in the Muslim world was an important factor. Gulf oil money was also a huge factor, in a phenomenon known as Petro-Islam.
The above reasons are generally agreed to be the ultimate causes of the Islamic revival. There were also specific political events which heralded the revival. Major historical turning points in the Islamic revival include, in chronological order:
- The Arab defeat in the 1967 Six-Day War helped to convince many Muslims that pan-Arabism failed to deliver on its promises. According to a common assessment offered at the time, "the Jews had deserved victory by being truer to their religion than the Arabs had been to theirs". After a period of introspection and rise of religious discourse, the Yom Kippur War of 1973 was fought in the name of Islam rather than pan-Arabism and the greater success of Arab armies was seen to validate the change.
- The energy crisis of the 1970s, which led to the formation of the Organization of Petroleum Exporting Countries (OPEC) and the quadrupling of global oil prices. At first, this led to an expectation that the oil wealth would lead to a long-awaited resurgence of the Islamic civilization, and when this failed to materialize, the mounting frustration with secular regimes made the public more receptive to religious fundamentalism. Scholar Gilles Kepel, agrees that the tripling in the price of oil in the mid-1970s and the progressive takeover of Saudi Aramco in the 1974–1980 period, provided the source of much influence of Wahhabism in the Islamic World, in the aforementioned phenomenon of Petro-Islam.
- The opening of the first Islamic bank in Dubai.
- The rise of the Mujahideen in Afghanistan in the late 1970s. The Mujahideen were a major beneficiary of Petro-Islam, and would ultimately lead to the rise of Al-Qaeda.
- Zia-ul-Haq introduces Islamic legal system in Pakistan.
- The return of Khomeini to Iran in 1979 and his establishment of a fundamentalist Islamic state. The Iranian revolution emboldened fundamentalists around the world.
- The Grand Mosque Seizure of 1979.
- The establishment of many Islamic banks in Turkey in the mid 1980s and the government recognition of these banks.
The term "Islamic revival" encompasses "a wide variety of movements, some intolerant and exclusivist, some pluralistic; some favorable to science, some anti-scientific; some primarily devotional, and some primarily political; some democratic, some authoritarian; some pacific, some violent".
The revival has been manifested in greater piety and a growing adoption of Islamic culture among ordinary Muslims. In the 1970s and 80s there were more veiled women in the streets. One striking example of it is the increase in attendance at the Hajj, the annual pilgrimage to Mecca, which grew from 90,000 in 1926 to 2 million in 1979.
Among revivalist currents, neo-fundamentalism predominates, stressing obedience to Islamic law and ritual observance. There have also been Islamic liberal revivalists attempting to reconcile Islamic beliefs with contemporary values and neo-Sufism cultivates Muslim spirituality;  Many revivalist movements have a community-building orientation, focusing on collective worship, education, charity or simple sociability. Many local movements are linked up with national or transnational organizations which sponsor charitable, educational and missionary activities.
A number of revivalist movements have called for implementation of sharia. The practical implications of this call are often obscure, since historically Islamic law has varied according to time and place, but as an ideological slogan it serves "to rally support for the creation of a utopian, divinely governed Islamic state and society".
According to scholar Olivier Roy,
The call to fundamentalism, centered on the sharia: this call is as old as Islam itself and yet still new because it has never been fulfilled, It is a tendency that is forever setting the reformer, the censor, and tribunal against the corruption of the times and of sovereigns, against foreign influence, political opportunism, moral laxity, and the forgetting of sacred texts.
Contemporary Islamic revival includes a feeling of a "growing universalistic Islamic identity" as often shared by Muslim immigrants and their children who live in non-Muslim countries. According to Ira Lapidus,
The increased integration of world societies as a result of enhanced communications, media, travel, and migration makes meaningful the concept of a single Islam practiced everywhere in similar ways, and an Islam which transcends national and ethnic customs.
But not necessarily transnational political or social organisations:
Global Muslim identity does not necessarily or even usually imply organised group action. Even though Muslims recognise a global affiliation, the real heart of Muslim religious life remains outside politics – in local associations for worship, discussion, mutual aid, education, charity, and other communal activities.
Scholarship and fiqh
Islamic revivalist leaders have been "activists first, and scholars only secondarily", emphasizing practical issues of Islamic law and impatient with theory. According to Daniel W. Brown, two "broad features" define the revivalist approach to Islamic authorities: distrust of Islamic scholarship along with "vehement rejection" of taqlid (accepting a scholar's decision without investigating it); and at the same time a strong commitment to the Quran and Sunnah.
Politically, Islamic resurgence runs the gamut from Islamist regimes in Iran, Sudan, and Taliban Afghanistan. Other regimes, such as countries in the Persian Gulf region, and the secular countries of Iraq, Egypt, Libya, and Pakistan, while not a product of the resurgence, have made some concessions to its growing popularity.
In reaction to Islamist opposition during the 1980s, even avowedly secular Muslim states "endeavoured to promote a brand of conservative Islam and to organise an `official Islam`". Official radio stations and journals opened up to fundamentalist preaching.
In 1971, the constitution of Egypt was made to specify (in article 2) that the sharia was "the main source of legislation". 1991 the Egyptian Security Court condemned the writer Ala'a Hamid to eight years in prison for blasphemy. By the mid 1990s, the official Islamic journal in Egypt – Al-Liwa al-Islami – had a higher circulation than Al-Ahram. The number of "teaching institutes dependent" on Al-Azhar University in Egypt increased "from 1985 in 1986–7 to 4314 in 1995–6".
In Pakistan, a bill to make sharia the exclusive source of law of the state was introduced after General Zia's coup in 1977, and finally passed in 1993 under Nawaz Sharif's government. The number of registered madrassas rose from 137 in 1947 to 3906 in 1995.
In Algeria, the leftist secularist FLN government made Friday an official holy day in 1976. The family law of 1984 "re-introduced some sharia elements" such as Quranic dissymmetry between men and women, and the official policy of Arabisation led to a de facto Islamisation of education.
In secular Turkey, religious teaching in schools was made compulsory in 1983. Religious graduates of İmam Hatip secondary schools were given right of access to the universities and allowed to apply for civil service positions, introducing it to religious-minded people.
Even the Marxist government of Afghanistan, before it was overthrown, introduced religious programs on television in 1986, and declared Islam to be the state religion in 1987.
In Morocco, at the end of the 1990s, more doctorates were written in religious sciences than in social sciences and literature. In Saudi Arabia, the absolute majority of doctorates were in religious sciences.
For the first time, the regime celebrated the Prophet's birth with greater fanfare than the anniversary of the ruling party. Billboards once heralding 'progressiveness and socialism' were also being replaced with new admonitions: 'Pray for the Prophet, and Do not forget to mention God.' President Bashar Assad had recently approved Syria's first Islamic university, as well as three Islamic banks. And Mohammed Habash, the head of the Islamic Studies Center, had been invited to speak on Islam at Syria's military academy – where praying had been banned 25 years earlier. ... In the 1980s, a distinct minority of women in Damascus wore hejab, or modest Islamic dress. In 2006, a distinct majority in Syria's most modern city had put it on.— Robin Wright, Dreams and Shadows: the Future of the Middle East
In many Muslim countries, there has been a growth of networks of religious schools. "Graduates holding a degree in religious science are now entering the labour market and tend, of course, to advocate the Islamisasion of education and law in order to improve their job prospects." 
In Iraq, Ayatollah Mohammad Baqir al-Sadr criticized Marxism and presented early ideas of an Islamic alternative to socialism and capitalism. Perhaps his most important work was Iqtisaduna (Our Economics), considered an important work of Islamic economics .
One observation made of Islamization is that increased piety and adoption of Sharia has "in no way changed the rules of the political or economic game", by leading to greater virtue. "Ethnic and tribal segmentation, political maneuvering, personal rivalries" have not diminished, nor has corruption in politics and economics based on speculation.