What is Polytheism? (Shirk)

The antonym of monotheism is polytheism. Polytheism is to ascribe partners to Allah. A Polytheist is someone ascribing partners to Allah. It means that you believe in the existence of a partner and equal of Allah. The biggest sin one can commit is polytheism.
The Creator has made known that He does not forgive a polytheist who dies without repentance and that this person will not enter Paradise. Without a doubt, the gates of repentance are open for polytheism as it is open for all other sins.
Relevant verses state the following:
“Indeed, Allah does not forgive association with Him, but He forgives what is less than that for whom He wills.” (Nisa, 4/48)
“Indeed, he who associates others with Allah - Allah has forbidden him Paradise, and his refuge is the Fire.” (Maʼidah, 5/72)
Why is polytheism the biggest sin? Because it directly extorts the rights of Allah.  Polytheism occurs in different forms. One of them is to associate partners to Him, believing that He has a likeness, an equal, a helper or a counterpart. This is called major shirk. Christians, for example, believed in monotheism –the oneness of Allah- at first. However, over time, they attributed some of His attributes to other beings and even deified Isa (Jesus). Father, Son and Holy Spirit became the three divine beings.
Another form of polytheism is excessive respect to people. The Messenger of Allah (saw) disliked being praised excessively and warned people about it: “Do not exaggerate in praising me as the Christians praised the son of Mary, for I am only a Slave. So, call me the Slave of Allah and His Apostle.” (Bukhari, al-Anbiya, 48)
From the Prophetic guidance, we learn this principle: Not a single person is at the level of a prophet. Since even Prophets are not given a status above humans, surely we should avoid deifying other people.
The reverence and respect that should be shown to Allah Almighty cannot be shown to anyone other than Him. In a sense, holding on to monotheism makes a person earn honor and character, and protects him from becoming vulgar and serving someone slavishly.
We as Muslims always control our feelings, thoughts and actions with regards to these topics. We are just as sensitive to sepulchers and entombed saints as we are to living people. We visit their tombs to learn from their experiences. We certainly do not ask and seek help from them. Because we only ask and seek help from our Lord.
Muslims believe that it is only the Prophets who are protected from sin and those who are innocent. So a person can be pious and have an excellent personality, people can benefit from his high moral and exemplary personality.
Nevertheless, all the virtues he has does not make him infallible and protected from sins. Nobody has been given a warranty of salvation. Only Allah knows His servants completely. 
A believer does not exaggerate in the praise of the person he respects. Neither does he see the person’s ideas, state and actions as errorless. Nobody will look at him as if he has guaranteed both this world and the Hereafter, as if he is incontestable.

11