The peril of shirk and the obligation to beware of it by avoiding its causes:

Shirk is the gravest of all sins, for Allah the Exalted has informed us that He will not forgive anyone who dies without repenting from it, even though He—glorified be He—has inscribed mercy upon Himself. This should fill every servant with the utmost caution and fear of a crime of such magnitude, and should impel him to learn what it is so that he can keep away from it. Indeed, it is the most heinous of evils and the darkest form of injustice; Allah says, “Verily, associating partners with Allah is a tremendous wrongdoing.” 2 It belittles Allah’s majesty and sets others as equals to Him, as He says, “Those who disbelieve equate others with their Lord,” 3 and, “So do not set up rivals to Allah while you know.” 4 Moreover, shirk stands in direct opposition to the very purpose for which creation and command exist in the first place.