Allah commanded His servant and Messenger, Muhammad , to call the People of the Two Scriptures and the unlettered idolators to his religion, way, Law and all that Allah sent him with. Allah said,

﴿وَقُلْ لِّلَّذِينَ أُوتُواْ الْكِتَـبَ وَالاٍّمِّيِّينَ ءَأَسْلَمْتُمْ فَإِنْ أَسْلَمُواْ فَقَدِ اهْتَدَواْ وَّإِن تَوَلَّوْاْ فَإِنَّمَا عَلَيْكَ الْبَلَـغُ﴾

(And say to those who were given the Scripture (Jews and Christians) and to those who are illiterates (Arab pagans): "Do you (also) submit yourselves'' If they do, they are rightly guided; but if they turn away, your duty is only to convey the Message.) meaning, their reckoning is with Allah and their return and final destination is to Him. It is He Who guides whom He wills and allows whom He wills to stray, and He has the perfect wisdom and the unequivocal proof for all of this. This is why Allah said,

﴿وَاللَّهُ بَصِيرٌ بِالْعِبَادِ﴾

(And Allah sees the servants.) for He has perfect knowledge of who deserves to be guided and who does not deserve to be guided. Verily,

﴿لاَ يُسْأَلُ عَمَّا يَفْعَلُ وَهُمْ يُسْـَلُونَ ﴾

(He cannot be questioned for what He does, while they will be questioned.) ﴿21:23﴾ because of His perfect wisdom and mercy. This and similar Ayat are clear proofs that the Message of Muhammad is universal to all creation, as it is well established in the religion, according to the various texts of the Book and Sunnah. For instance, Allah said,

﴿قُلْ يَأَيُّهَا النَّاسُ إِنِّى رَسُولُ اللَّهِ إِلَيْكُمْ جَمِيعًا﴾

(Say (O Muhammad ): "O mankind! Verily, I am sent to you all as the Messenger of Allah.'') ﴿7:158﴾, and,

﴿تَبَارَكَ الَّذِى نَزَّلَ الْفُرْقَانَ عَلَى عَبْدِهِ لِيَكُونَ لِلْعَـلَمِينَ نَذِيراً ﴾

(Blessed be He Who sent down the criterion to His servant that he may be a warner to the `Alamin (mankind and Jinn).) ﴿25:1﴾.

The Two Sahihs and other collections of Hadith recorded that the Prophet sent letters to the kings of the earth during his time and to different peoples, Arabs and non-Arabs, People of the Book and the unlettered, just as Allah had commanded him. `Abdur-Razzaq recorded that Ma`mar said, that Hammam said that Abu Hurayrah said that the Prophet said,

«وَالَّذِي نَفْسِي بِيَدِهِ، لَا يَسْمَعُ بِي أَحَدٌ مِنْ هَذِهِ الْأُمَّةِ: يَهُودِيٌّ وَلَا نَصْرَانِيٌّ، وَمَاتَ وَلَمْ يُؤْمِنْ بِالَّذِي أُرْسِلْتُ بِهِ، إِلَّا كَانَ مِنْ أَهْلِ النَّار»

(By He in Whose Hand is my soul! No member of this Ummah, no Jew or Christian, hears of me but dies without believing in what I was sent with, but will be among the people of the Fire.) Muslim recorded this Hadith.

The Prophet said,

«بُعِثْتُ إِلَى الْأَحْمَرِ وَالْأَسْوَد»

(I was sent to the red and black. ) and,

«كَانَ النَّبِيُّ يُبْعَثُ إِلى قَوْمِهِ خَاصَّةً، وَبُعِثْتُ إِلَى النَّاسِ عَامَّة»

(A Prophet used to be sent to his people, but I was sent to all mankind.)

﴿إِنَّ الَّذِينَ يَكْفُرُونَ بِآيَـتِ اللَّهِ وَيَقْتُلُونَ النَّبِيِّينَ بِغَيْرِ حَقٍّ وَيَقْتُلُونَ الَّذِينَ يَأْمُرُونَ بِالْقِسْطِ مِنَ النَّاسِ فَبَشِّرْهُم بِعَذَابٍ أَلِيمٍ - أُولَـئِكَ الَّذِينَ حَبِطَتْ أَعْمَـلُهُمْ فِي الدُّنْيَا وَالاٌّخِرَةِ وَمَا لَهُم مِّن نَّـصِرِينَ ﴾

(21. Verily, those who disbelieve in the Ayat of Allah and kill the Prophets without right, and kill those men who order just dealings, then announce to them a painful torment.) (22. They are those whose works will be lost in this world and in the Hereafter, and they will have no helpers.)