The Iblees are demons in Muslim theology. The Iblees’ evil is of six types, but I will quote the description of only the two first types.
THE FIRST ONE IS THE EVIL OF KUFR AND SHIRK: enmity to Allah (subhanahu wa ta’aala) and His Messenger (sallallaahu ‘alaihi wa sallam). If he gains this from the son of Adam, his moaning is eased, and he rests from his ordeal. Further, this is the first thing Iblees wants from the worshipper (al-’Abd). If Iblees gains this, he makes this person part of his army, one of his soldiers, and he appoints him as a deputy or agent against other human beings.
If he despairs of enticing him with the first evil, and if this person is one of those for whom it was written that he would be a Muslim in his mother’s womb, Iblees tries the SECOND CLASS OF EVIL. This is BID’AH (innovation). Iblees loves Bid’ah more than debauchery and disobedience because the harm of Bid’ah is in the essence of the religion. Moreover, it is an unrepentable sin and is against the call of the messengers and is a call to a message different from the one conveyed by Ar-Rasool. If Iblees gains the performance of Bid’ah from a person and makes him one of the people of Bid’ah, he also becomes one of his agents and a caller of his.