Kufr in Islam: what is it and what are it’s types :
Learning about Kufr is an essential part of Muslim’s knowledge about his faith. Without knowing Kufr, you cannot do justice to Tawheed. Kufr is used in the Glorious Qur’an for people who cover up or hide the truth. It also uses this word to point out those who denied the favors of Allah by not accepting his Dominion and Authority. Therefore Kufr is the opposite of Imaan or Disbelief in Allah and a Non-Believer is called Kaafir.
A person can be categorized as Kaafir or Murtadd (meaning apostate) if the following twelve beliefs or actions...
From that which has been established in the Sharee'ah (prescribed law) is that mankind was - in the beginning - a single nation upn true Tawheed, then Shirk (directing any part or form of worship, or anything else that is solely the right of Allah,
to other than Allah) gradually overcame them. The basis for this is the saying of Allah - the Most Blessed, the Most high:
"Mankind was one Ummah, then Allah sent prophets bringing good news and warnings." (Surah Baqarah 2:213)
Ibn 'Abbas - radiallaahu 'anhu - said:
"Between Nooh (AS) (Noah) and Adam (AS) were ten generations, all of them were upon...