Mahmud was one of the supporters of Mossadeq and a candidate in the 1952 parliamentary election. Mahmud worked on a Qur'anic commentary in which he concluded that Muslims had to take their destiny into their own hands and strive against internal and external foes to achieve justice and improve their lot. He co-founded the Liberation Movement of Iran with Mehdi Bazargan in 1961, hence arrested as a result in 1963 but was freed in 1978. Mahmud was a key-figure in the Islamic Revolution of 1978-1979. He led the anti-regime demonstration of 10th and 11th December 1978 in Tehran, which brought the end of the Shah's regime. Mahmud was born in Taleqan valley north-west of Tehran.