Kufr

Its original meaning is 'to conceal'. This word has been variously used in the Quran to denote: (1) state of absolute lack of faith; (2) rejection or denial of any of the esentials of Islam; (3) attitude of ingratitude and thanklessness to God; and (4) non-fulfilment of certain basic requirements of faith. In the accepted technical sense, kufr consists of rejection of the Divine Guidance communicated through the Prophets and Messengers of God. More specifically, ever since the advent of the last of the Prophets and Messengers, Muhammad (S.A.W.), rejection of his teaching constitutes Kufr.