In 1868 he left for Isfahan to study Islamic sciences at one of the religious colleges in the city; he was given a room by one of the prayer leaders, Imam-Jumʻih, Sayyid Muhammad Sultanu'l-ʻUlama, who was a friend of his father's.
[1] In October 1873, Mírzá Abu'l-Faḍl was invited to Tehran to teach Kalam, or speculative theology, at the Madrasih Hakim Hashim, one of the religious colleges in the city.
He also discussed the history of religion with two Buddhist scholars who were in Tehran at the same time, and attended science classes at the élite school of Dar ol-Fonoon, founded by Amir Kabir, the grand vizier to Nasereddin Shah.
Abu'l-Faḍl, at one point, met an uneducated cloth-seller, named Aqa ʻAbdu'l-Karim, with whom he would have discussions over difficult religious questions.
As soon as he became a Baháʼí, Abu'l-Faḍl began to teach the new religion to others, and when news spread of his conversion away from Islam, he was removed from the religious college.
During his time at the school, a number of Zoroastrians converted to the Baháʼí Faith including Ustad Javanmard and Mulla Bahram Akhtar-Khavari.
It was principally through his writings that the Baháʼí Faith was presented to the Jews of Iran in such a way as to bring a large number of them into accepting Baháʼu'lláh.
[1] Between 1900 and 1904 he travelled to Paris and the United States, by request of ʻAbdu'l-Bahá, where his talks and writings enabled the fledgling Baháʼí communities to gain confidence and a clear understanding of the religion.
Then in the autumn of 1901 he travelled to the United States, and specifically to Chicago, where the largest Baháʼí community was, and gave a large number of talks.
In 1904, ʻAbdu'l-Bahá asked that Abu'l-Faḍl return to the Middle East, and the Baháʼís held a large farewell gathering for him in New York City on 29 November 1904.
[1] Momen states that Abu'l-Faḍl's writings "show a keen understanding of modern currents of thought remarkable in a man who only knew oriental languages."
[1] Mírzá Abu'l-Faḍl wrote on a wide range of Baháʼí subjects, including extensive amounts of material about the proofs of Baháʼu'lláh's mission.