Imam Khomeini became a Marja in 1963, following the death of Grand Ayatollah Seyyed Hossein Borujerdi.
Although during this scholarly phase of his life Imam Khomeini was not politically active, the nature of his studies, teachings, and writings revealed that he firmly believed from the beginning in political activism by clerics.
Three factors support this suggestion. First, his interest in Islamic studies surpassed the bounds of traditional subjects of Islamic law (Sharia), jurisprudence (Fiqh), and principles (Usul) and the like.
He was keenly interested in philosophy and ethics.
Second, his teaching focused often on the overriding relevance of religion to practical social and political issues of the day.
Third, he was the first Iranian cleric to try to refute the outspoken advocacy of secularism in the 1940s. His now well-known book, Kashf-e Asrar (Discovery of Secrets) was a point by point refutation of Asrar-e Hezar Saleh (Secrets of a Thousand Years), a tract written by a disciple of Iran's leading anti-clerical historian, Ahmad Kasravi. Also he went from Qom to Tehran to listen to Ayatollah Hassan Modarres —the leader of the opposition majority in Iran's parliament during 1920s.
Only two weeks after the Shah fled Iran on January 16, 1979, Imam Khomeini returned to Iran triumphantly, on Thursday, February 1, 1979, invited by the anti-Shah revolution which was already in progress.
Conservative estimates put the welcoming crowd of Iranians at least three million. When Imam Khomeini was on plane on his way to Iran after many years in exile, a reporter, Peter Jennings asked him: "What do you feel?" and surprisingly Imam Khomeini answered "Nothing!"
In a speech given to a huge crowd on the first day of returning to Iran, Imam Khomeini attacked the government of Shapoor Bakhtiar promising "I shall punch their teeth in."
He also made a variety of promises to Iranians for his coming Islamic regime: A popularly elected government that would represent the people of Iran.