Sheikh Khâlid al-Sayf, professor at al-Imâm University
Ever since Muhammad (peace be upon him) was sent with the Message, all people who do not believe that Muhammad (peace be upon him) is God's Messenger to all humanity are classified as unbelievers with respect how they are categorized in matters pertaining to this worldly life. This applies to the people of the Scripture – in other words, Jews and Christians – as well as to people who belong to other faith traditions.
It makes no difference whether the people in question are from among their religion's clergy and religious scholars, or from among its laity.
The Qur'an makes this clear, since it refers to Jews and Christians who reject Muhammad as being unbelievers.
Allah says: "They surely disbelieve who say: 'Lo! Allah is the Messiah, son of Mary.' The Messiah (himself) said: 'O Children of Israel, worship Allah, my Lord and your Lord. Lo! Whoever ascribes partners unto Allah, for him Allah has forbidden Paradise. His abode is the Fire. For evil-doers there will be no helpers.' " [Sûrah al-Mâ'idah: 72]
Allah says: "They surely disbelieve who say: Allah is one of three in a Trinity." [Sûrah al-Mâ'idah: 74]
Allah says: "Lo! Those who disbelieve in Allah and His messengers, and seek to make distinction between Allah and His Messengers, and say: 'We believe in some and disbelieve in others', and seek to choose a way in between; such are disbelievers in truth; and for disbelievers We have prepare a shameful doom." [Sûrah al-Nisâ': 150-151]
In these verses, the Qur'an makes no distinction between the general masses and the clergy. Therefore, the general following of Christianity, Judaism, and all other religions that reject the prophethood of Muhammad (peace be upon him) are referred to as unbelievers according to the terminology of Islamic Law.
This means that the worldly rulings pertaining to interrelating with unbelievers apply to them; for instance, the laws of inheritance and other similar rulings. This, however, only pertains to their legal status in this world.
As for the fate of particular individuals in the Hereafter, that is entirely up to Allah to decide. Allah will judge each individual according to His knowledge and wisdom.
It is a tenet of faith adhered to by all Sunni Muslims (Ahl al-Sunnah wal-Jamâ`ah) that no particular individual is ever to be declared a denizen of Heaven or of Hell except for those few explicitly named individuals whose fates are stated in the text of the Qur'an or in the Sunnah of the Prophet (peace be upon him).
For instance, we know about the ten Companions whom the Prophet Muhammad (peace be upon him) gave glad tidings of their being admitted into Heaven. We also know that Abu Lahab will be in Hell, since the Qur'an informs us of his fate.
And Allah knows best.
Source: Islam Today