Like any other translations, the translation of the Qur'an must be made according to the principles of translation. Despite the great efforts of the translators of the Qur'an in Persian, problems can be found in these translations. One of the terms whose translation needs to be defined precisely is the term "faith". This term and its derivatives are used in the Qur'an in two forms: one in transitive sense with the preposition "bā" in Arabic and the other one with preposition "lam". Etymologists and Shia and Sunni commentators, by examining the meaning of "faith" in its latter usage, have expressed different opinions about it. Drawing upon the descriptive-analytical method and reflecting on the Qur'anic usages of the term "faith" in its former usage and comparing it with the usages of "faith" in its latter usage in 28 Persian translations of the Qur'an, and also by referring to the lexical and explanatory books on the Qur'an, this article has shown that except for a small number of translations, the rest of them do not have the necessary accuracy and have not provided a correct translation. The findings of this research work is that the term "faith" in its former usage means "faith" as opposed to disbelief, and the term "faith" in its latter usage means confession and submission; which finds its meaning in Persian in the word trust.