As much as a Muslim learns about Islam and the beauty of it, the more a Muslim fears about falling in to the abyss of the Hellfire.
An imprtant aspect of Islam that is most abused these daysis the knowledge of kufr and it’s types. This knowledge is not acquired so that one becomes judgemental of others, rather it becomes a tool to keep oneself from falling in to it, and we seek the Help of Allah from the evils of our own souls and the accursed shaitan.
And as for the Major Kufr (kufr akbar) – then it is of five types :Kufr of takdheeb (rejection), kufr due to arrogance and pride whilst one acknowledges the truth (tasdeeq), kufr of I’raad (turning away), kufr of shakk (doubts) and kufr of nifaaq (hypocrisy). … More IBN AL-QAYYIM ON TYPES OF KUFR – MADARIJ US-SALIKEEN PAGES 335-338 – TRANSLATED TO ENGLISH