Excess in all things including religion will impair critical thinking. which is probably one reason Islam stresses moderation in all things including religion.
The Prophet Muhammad (peace be upon him) said: "The good deeds of any person will not make him enter Paradise (i.e., no one enters paradise only through his good deeds)." The Prophet's companions asked: "Not even you?" The Prophet replied: "Not even myself, unless God bestows His favor and mercy on me. So be moderate in your religious deeds and do what is within your ability. None of you should wish for death, for if he is a doer of good, he may increase his good deeds, and if he is an evil doer, he may repent to God." - Sahih al-Bukhari, Volume 7, Hadith 577