If, concerning a fact which is to be believed, one consults experimental knowledge and believes it when it is suitable with experiments but disbelieves or doubts it when one cannot prove it through experiments, one has believed experiments, not the Messenger. Such iman, let alone being perfect, is not iman itself. For iman cannot be broken. It cannot be great or small.
If one attempts to measure religious knowledge with philosophy, one has believed the philosopher, not the Prophet. [Yes, mind, philosophical and experimental knowledge are of great help in realizing that Allahu ta’ala exists and that Muhammad ‘alaihissalam’ is Allah’s Prophet. But, after believing the Prophet with their help, it is not right to consult mind, philosophy, or experimental knowledge about any of the facts communicated by him. For, as shown by some examples appearing in literature, many of the facts acquired through mind, philosophy and experimentation change in the process of time, and when new ones are found old ones are discarded.]
Then, Iman is to trust and believe all the commandments which our master Rasulullah ‘sallallahu alaihi wa sallam’, as the Prophet, brought and conveyed to all people from Allahu ta’ala.