First, the term "humanist" was given to the educated elite that had been greatly interested in the Greek and Roman culture; the elite that expressed itself through literature, art, and daily behaviors more than through philosophical discourse. This atmosphere was considered as a coup against the Church and all Christian heritage inherited from the Middle Ages. However, all this was done without giving any other proposal or alternative except the liberation from any authority, and the call for individualism, starting with thought and ending with behavior. Humanism believes in the instrumental reason to the extent of sanctification. The ideas of t humanists had dominated over most of the horizons of thought. In fact, they have subconsciously dominated over our thoughts as learned people. So, the reading of books was no longer related to the date or circumstances of their origins, which led to a closure of consciousness among the Islamists in particular; as a result of their strong abidance by inherited beliefs, that often led to extreme actions. In this article, we follow the deductive approach through observing the process of founding the thought of humanism by studying its foundations, and then analyzing them. We have concluded that the best way in dealing with humanism, as a modern intellectual theory, is to be with no excessiveness nor negligence, but through studying it deliberately and criticizing it objectively.