The sin of shirk is to associate partners with Allah, basically this means to set up idols and false deities alongside Allah, granting them equal status to Allah, and to give them actions which are only reserved for Allah alone, such as worshipping them, making oaths to them, having fear and hope in them, and to sacrifice things in their name. All of this constitutes shirk, an example is the case of Jesus, those who set him up as a God, and invoke on him and pray to him are guilty of shirk, they are guilty of setting up a partner to Allah.
There are many ways of committing shirk, and it is to this that we turn our attention to in this
lecture because it is very important to know the routes that lead to shirk, because when one
knows this information it allows him to guard himself against it.