The Personal Obligatory Knowledge of Islam 

The Personal Obligatory Knowledge of Islam is a necessary portion of Islamic knowledge which is obligatory upon every accountable person to acquire; otherwise one is sinful.  Such knowledge entails matters of belief in Allah, His Angels, His Books, His Messengers, the Day of Judgment, Destiny, and the like. It also includes matters of purification, prayer, fasting, zakah (type of financial obligation) upon the liable, pilgrimage upon the able, and the sins of the heart, hands, eyes, and the like. 

Suratuz-Zumar, Ayah 9 means,

“Those who know are not equal to those who do not know.” Prophet Muhammad, sallallahu ^alayhi wa sallam, said, “Seeking the knowledge of the Religion is obligatory upon every Muslim,” (i.e., male and female). (Related by al-Bayhaqiyy)