Lesson 3: There are six pillars of faith: Belief in Allah, His Angels, His Revealed Books, His Messengers, the Last Day, and Divine Destiny, good and bad.

Lesson 4: Tawhid (monotheism or oneness) has three categories: Tawhid Al­Rububiyyah (Oneness of the Lordship of Allah), Tawhid Al­Uluhiyyah (Oneness of the Worship of Allah) and Tawhid Al­Asma' Wa Al­Sifat (Oneness and uniqueness of the Names and Attributes of Allah).

Shirk (polytheism) has also three categories: Shirk Akbar (major polytheism), Shirk Asghar (minor polytheism) and Shirk Khafiy (hidden polytheism).

Major polytheism makes the deeds of those who commit it vain and fruitless. It also causes those who commit it to remain in Hell­Fire for all eternity, as Allah (Exalted be He) says, But if they had joined in worship others with Allâh, all that they used to do would have been of no benefit to them. Allah also says: It is not for the Mushrikûn (polytheists, idolaters, pagans, disbelievers in the Oneness of Allâh), to maintain the Mosques of Allâh (i.e. to pray and worship Allâh therein, to look after their cleanliness and their building,), while they witness against their ownselves of disbelief. The works of such are in vain and in Fire shall they abide.

Hence, Allah (Exalted be He) will not forgive those who commit this type of polytheism and die without repentance. Also, they will not be admitted into the Paradise; as Allah (Exalted be He) says, Verily, Allâh forgives not that partners should be set up with Him (in worship), but He forgives except that (anything else) to whom He wills He (Glorified be He) also says, Verily, whosoever sets up partners (in worship) with Allâh, then Allâh has forbidden Paradise to him, and the Fire will be his abode. And for the Zâlimûn (polytheists and wrong­doers) there are no helpers.

This type of polytheism includes, among other things, seeking assistance from the dead and idols, supplicating to them, making vows in their names, and offering sacrifices to them.