All praise be to Allaah, the Lord of the worlds, and peace and blessings be upon our Prophet Muhammad, the truthful and honest one, and upon all his family and Companions!
Allaah (Glorified and Exalted be He) sent Prophets and Messengers to invite people to Tawheed (belief in the Oneness of Allaah), to sincerely worship Allah Alone, and to explain the Sharee‘ah (Islaamic Law) that He ordained for His Servants. He created humans and Jinn (creatures created from fire) for this purpose. Allaah (Glorified be He) says (what means): And I (Allaah) created not the jinn and mankind except that they should worship Me (Alone). He (Glorified and Exalted be He) also says: And verily, We have sent among every Ummah (community, nation) a Messenger (proclaiming): “Worship Allaah (Alone), and avoid (or keep away from) Taaghoot (all false deities i.e. do not worship Tâghût besides Allaah).”
Allaah (Glorified be He) says that He never punishes a people until after He has sent them a bearer of good news and a warner. He (Exalted be He) says… read more here.