Mahmoud Mohammed Taha, (1909 – 18 January 1985; Arabic: محمود محمد طه) also known as Ustaz Mahmoud Mohammed Taha, was a Sudanese religious thinker, leader, and trained engineer. He developed what he called the "Second Message of Islam", which postulated that the verses of the Qur'an revealed in Medina were appropriate in their time as the basis of Islamic law, (Sharia), but that the verses revealed in Mecca represented the ideal and universal religion, which would be revived when humanity had reached a stage of development capable of implementing them, ushering in a renewed era of Islam based on the principles of freedom and equality. He was executed for apostasy for his religious preaching at the age of 76 by the regime of Gaafar Nimeiry.

Taha was born in a village near Rufaa, a town on the eastern bank of the Blue Nile, 150 kilometres (93 mi) south of Khartoum. He was educated as a civil engineer in a British-run university in the years before Sudan's independence. After working briefly for Sudan Railways he started his own engineering business. In 1945, he founded an anti-monarchical, federalist and socialist political group, the Republican Party, and was twice imprisoned by the British authorities.

In September 1946, Taha led a protest against the arrest of a women who circumcised her daughter, which was panned in 1945. He was tried and sentenced to two years in Wad Madani by Judge Muhammad Ahmad Abu Rannat.

Taha developed what he called "Second Message of Islam" after a period of prolonged "religious seclusion". His message argues that contrary to mainstream Islam, the classical Shariah (Islamic law) was intended for Muhammad's rule in Medina and not for all times and places.

Muslims believe that Quran is made up of Meccan surahs (chapters of the Quran believed to have been revealed before the Hijra—the migration of the Islamic prophet Muhammed and his followers from Mecca to Medina) -- and Medinan surahs (chapters believed to have been revealed after the Hijra). The Meccan verses are "suffused with a spirit of freedom and equality, according to Taha, they present Islam in its perfect form"; the Medinian verses are "full of rules, coercion, and threats, including the orders for jihad". Taha believed that they "were a historical adaptation to the reality of life in a seventh-century Islamic city-state, in which 'there was no law except the sword.'”

These later Medinan verses, form the basis for much of Sharia, which Taha calls the “first message of Islam”.

The two kinds of verse were often in contradiction. The Meccan verses saying things like "You [Muhammad] are only a reminder, you have no dominion over them”; Medinan speak of the "duties and norms of behavior" in Islam, such as: “Men are the managers of the affairs of women for that God has preferred one of them over another..." (Q.4:34).

Taha argued, in effect, the opposite of this classical basis of law. He believed that the "Medina Qur'an", and Sharia laws based on them, were "subsidiary verses" – suitable for 7th century society, but "irrelevant for the new era, the twentieth century", violating the values of equality, religious freedom and human dignity. Meccan verses, making up the "Second Message" of Islam, should form the "basis of the legislation" for modern society.