166. To ask believers to believe might at first seem strange. The fact is, however, that belief as used here has two meanings. First, belief denotes that a man has preferred to acknowledge the soundness of true guidance, to distance himself from the fold of those who disbelieve, and to join the camp of the believers. Second, belief denotes faith, a man's believing in the truth with all his heart, with full earnestness and sincerity. It denotes man's sincere determination to mould his way of thinking, his taste and temperament, his likes and dislikes, his conduct and character, his friendship and enmity, and the direction of his efforts and striving, in conformity with the creed which he has resolved to embrace. This verse is addressed to all those who are 'believers' in the first sense of the term, and they are asked to change themselves into true believers, i.e. believers in the second sense.
167. Kufr has two meanings. One signifies categorical rejection. The other signifies that pretence of belief even when either one's heart is not convinced or one's conduct is flagrantly opposed to the demands of one's belief. Here the term Kufr conveys both meanings, and the verse aims at impressing upon people that whichever kind of Kufr they adopt in respect of the fundamental beliefs of Islam, it will only alienate them from the Truth, and lead them instead to falsehood, and ultimately to their tragic failure and destruction.