The source of all evil is the deviation from the truth and its straight path. The goodness of all matters is the following of truth and adherence to its right way. Truth is the fixed state in which Allah has created every creature in a particular way and managed its affair in a certain manner. Allah is Perfect and exempt from any deficiency or error. This book aims to elucidate the pillars of Emaan (basis of belief, faith) and the characteristics of Kufr (disbelief) and its causes.