According to Islam the worst sin a person can commit is shirk. This sin is also called association.
This means associating Allah with a man. Professing that Jesus is the Son of Allah is the worst sin in Islam[/b]! According to the Koran,
Allah forbids heaven to anyone who commits this sin and their abode is hell without any help.
In Islam, shirk (Arabic: شرك širk) is the sin of practicing idolatry or polytheism, i.e. the deification or worship of anyone or anything besides the singular God, i.e. Allah. Literally, it means ascribing or the establishment of "partners" placed beside God. It is the vice that is opposed to the virtue of Tawhid (monotheism).[1]
Those who practice shirk are termed mushrikun.[2]
Within Islam, shirk is an unforgivable crime if it remains unpardoned before death: Allah may forgive any sin if one dies in that state except for committing shirk.[1][3]
The word širk comes from the Arabic root Š-R-K (ش ر ك), with the general meaning of "to share".[4] In the context of the Quran, the particular sense of "sharing as an equal partner" is usually understood, so that polytheism means "attributing a partner to Allah". In the Qur'an, shirk and the related word mušrikūn (مشركون)—those who commit shirk and plot against Islam—often refer to the enemies of Islam (as in verse 9.1–15).
Muslim philosophers identified belief in the Trinity with the heresy of shirk, in Arabic, meaning "associationism", in limiting the infinity of Allah by associating his divinity with physical existence.[8]
In a theological context one commits shirk by associating some lesser being with Allah. This sin is committed if one imagines that there is a partner with Allah whom it is suitable to worship. It is stated in the Quran: "
Allah forgives not that partners should be set up with Him, but He forgives anything else, to whom He pleases,
to set up partners with Allah is to devise a sin most heinous indeed" (Qur'an 4:48).
sourcequr'an 98.6: Those who reject (Truth), among the People of the Book and among the Polytheists, will be in Hell-Fire, to dwell therein (for aye).
They are the worst of creatures So the worst possible sin is to associate partners with allah (the lie that Christians associate Jesus with allah) is the worst possible sin.
Christians are hated for their shirk, so they are persecuted by muslims (hating what allah hates).
We have seen the real muslims and their abuse of Christians, now we have some backslider telling us it's all misinterpreted.