Henry Martyn (1781—1812), an English priest, during his tenure in India, decided to introduce Christianity not only among the Hinduists, but also among the Arabs and Persians, so he began translating the New Testament into Arabic and Persian to this end. In 1811, being a little familiar with Persian language and literature, he came to Iran and showed his translation to Iranian scholars who found it rather childish. Martyn resumed translating and had another trip to Shiraz to improve his Persian language skills. While in Shiraz, he confronted and challenged the Shiite clerics. His intention was to propagate Christianity, and he thus aimed more to invite and challenge the youth. Meanwhile, several treatises were written in response to his questions and doubts about Islam, and he also tried to refute these treatises in due course. The research was based on the archival record, and its main goal was to reveal and interpret the content of the messages of the Shiite clerics in response to Martyn's judgments as well as the content of Martyn's own responses to them. It turns out that during these religious debates and the opinion exchange between Islamic treatises and Martyn's writings, the missioner's utterances became less and less valuable to the Iranians, and especially to those who accepted his views, but he did not give up until Mohammad Reza Ibn Mohammad Amin Hamedani wrote the treatise “Guidance of the Misguided” to dispel Martyn's doubts. This treatise was the culmination of Martyn's anti-Islamic rhetoric in Iran. Failing to fulfill his religious mission, he left Iran without achieving his main goal of meeting Fath Ali Shah and Abbas Mirza to present the Persian version of the New Testament to them with his own hands, and soon after, on his way back home, he died in Turkey.