Allah does not forgive polytheists

Q 2: Why does Allah dispraise polytheism and threaten polytheists with everlasting punishment in Hellfire? A: Allah abhors polytheism and threatens polytheists that He will not forgive them and will cause them to undergo the perpetual residence in Hell if they die without repenting and quitting polytheism. Indeed, it is the most grievous sin and the greatest thing which Allah prohibited. Therefore, Allah (Glorified be He) informed us that He does not forgive its doer if he dies as a disbeliever and does not repent of his polytheistic actions. Moreover, his good deeds will be void, as none is more deviated than him. Allah (Exalted be He) says, Verily, Allâh forgives not that partners should be set up with Him (in worship), but He forgives except that (anything else) to whom He wills; and whoever sets up partners with Allâh in worship, he has indeed invented a tremendous sin. And He also says, ...Verily joining others in worship with Allâh is a great Zûlm (wrong) indeed. So anyone who associates others with Allah is equating between the Creator and His creation and makes the creature a rival to Allah and assigns to him the acts of worship which they do not deserve. Therefore, Allah threatens its doer with perpetual residence in Hell. Allah (Glorified is He) says, Verily, whosoever sets up partners (in worship) with Allâh, then Allâh has forbidden Paradise to him, and the Fire will be his abode. And for the Zâlimûn (polytheists and wrong-doers) there are no helpers. (Part No. 1; Page No. 344

A: Allah abhors polytheism and threatens polytheists that He will not forgive them and will cause them to undergo the perpetual residence in Hell if they die without repenting and quitting polytheism. Indeed, it is the most grievous sin and the greatest thing which Allah prohibited. Therefore, Allah (Glorified be He) informed us that He does not forgive its doer if he dies as a disbeliever and does not repent of his polytheistic actions. Moreover, his good deeds will be void, as none is more deviated than him. Allah (Exalted be He) says, Verily, Allâh forgives not that partners should be set up with Him (in worship), but He forgives except that (anything else) to whom He wills; and whoever sets up partners with Allâh in worship, he has indeed invented a tremendous sin. And He also says, ...Verily joining others in worship with Allâh is a great Zûlm (wrong) indeed. So anyone who associates others with Allah is equating between the Creator and His creation and makes the creature a rival to Allah and assigns to him the acts of worship which they do not deserve. Therefore, Allah threatens its doer with perpetual residence in Hell. Allah (Glorified is He) says, Verily, whosoever sets up partners (in worship) with Allâh, then Allâh has forbidden Paradise to him, and the Fire will be his abode. And for the Zâlimûn (polytheists and wrong-doers) there are no helpers. (Part No. 1; Page No. 344)  When the Prophet (peace be upon him) was asked, "Which sin is the greatest?" He said, "To make a rival to Allah although He created you." It is said, "What is next?" He said, "To kill your children for fear that they join you in food." It is said, "What is next?" It is said, "To have sex with the wife of your neighbor." So Allah revealed, And those who invoke not any other ilâh (god) along with Allâh, nor kill such person as Allâh has forbidden, except for just cause, nor commit illegal sexual intercourse