On the Concept of Iman. Faith (iman) means to affirm and verify the truth of someone’sreport in total trust. The concept of tasdiq, which holds the sense of sincere appropriation andacceptance in addition to its meaning of affirming necessary knowledge or reasoning (nazar) andthe knowledge inferred from evidence (istidlal), occupies a significant place in the definition ofiman. Having also the cognitive and existential aspects that include a candid embracement, faithis a phenomenon that takes place and is felt in the heart. Therefore, what is essential in iman is theaffirmation of the heart. Reason and the term qalb that occurs in the Qur’an are almost identicalterms. For this reason, there is a strong relationship between faith, reason, and knowledge