Shirk

Shirk - To associate partners with Allah in any manner. It is the gravest sin in Islam for which Allah states a person will not be forgiven for if he dies upon it. It is the chief sin of the disbelievers and takes on various forms: From open idol worship, to giving the characteristics of Allah to His creation (as Christians do with Jesus, (Alayhi Salam)), to attributing to Allah the characteristics of his creation (as do the Jews), to making invocations or supplications for assistance or blessings to other than Allah (as do some deviant Muslims).

Associating partners with Allah by giving Allah’s attributes to created things or giving Allah the attributes of created things. (Polytheism and it is worship others along with Allah)