• In the past, countries of the world were distant from each other; cities of the same country were far away from each other. The languages and sublanguages were very much different, and the transport and communication were very difficult.
To each nation, God sent one or more apostles to warn them of the punishment in the World and the afterlife, in case they wrong people and associate others with Him.
Even to each big city, He sent one or more apostles, and sometimes at the same time, there were more than one prophets and apostles.
The message is the same: to worship God alone, similar to the First Commandment.
What we were told is only concerning our region: Only some chief prophets of the Children of Israel, some prophets before them like Noah, Abraham, Salih, Hood, Shuaib, Jonah, etc.
Other nations must have had their apostles and warners, but we were not told about them in the Quran; because this requires extensive writings.
As in the aya 35: 24
إِنَّا أَرْسَلْنَاكَ بِالْحَقِّ بَشِيرًا وَنَذِيرًا وَإِن مِّنْ أُمَّةٍ إِلَّا خلَا فِيهَا نَذِيرٌ
The explanation:
(We have sent you [Mohammed] with the true [religion, as] a bearer of glad tidings and as a warner; and there was not any [past] nation, but a warner [of them] should have passed away therewith.)
However, when the apostle comes to his people, and speaks with them by their language, and then they divide into two parties according to God's guidance and misguidance.
This is in the Quran 14: 4
وَمَا أَرْسَلْنَا مِن رَّسُولٍ إِلاَّ بِلِسَانِ قَوْمِهِ لِيُبَيِّنَ لَهُمْ فَيُضِلُّ اللّهُ مَن يَشَاء وَيَهْدِي مَن يَشَاء وَهُوَ الْعَزِيزُ الْحَكِيمُ
The explanation:
(We did not send any messenger [before you, O Mohammed] but [to teach] in the language of his [own] people, in order to explain to them.
So God would lead astray those whom He please and would guide whom He please,
and He is the Almighty, the Most Wise.)
This is about the Quran did not reach a large number of people all over the world:
No, almost most people heard about the Quran; and the Quran meaning have been translated to a large number of languages, and this will be against people who do not believe; because they have already heard about the Quran and the Islam.
• The reason for the schism and fighting:
The reason for fighting and schism is not because of the religion of God itself; but because of their deviation from it.
This is in the Quran 5: 14
وَمِنَ الَّذِينَ قَالُواْ إِنَّا نَصَارَى أَخَذْنَا مِيثَاقَهُمْ فَنَسُواْ حَظًّا مِّمَّا ذُكِّرُواْ بِهِ فَأَغْرَيْنَا بَيْنَهُمُ الْعَدَاوَةَ وَالْبَغْضَاء إِلَى يَوْمِ الْقِيَامَةِ وَسَوْفَ يُنَبِّئُهُمُ اللّهُ بِمَا كَانُواْ يَصْنَعُونَ
The explanation:
(With those – [Christians] saying: "We ratified a covenant, but they have forgotten a portion of that they were admonished with; so We have stirred up enmity and hatred among them [and they divided into many sects] till Doomsday, and God assuredly will inform them [on the Day of Judgment] of the [statues of the Christ and his mother and the crosses] they used to make.)
This also is in the Quran 2: 253
وَلَوْ شَاء اللّهُ مَا اقْتَتَلَ الَّذِينَ مِن بَعْدِهِم مِّن بَعْدِ مَا جَاءتْهُمُ الْبَيِّنَاتُ وَلَكِنِ اخْتَلَفُواْ فَمِنْهُم مَّنْ آمَنَ وَمِنْهُم مَّن كَفَرَ وَلَوْ شَاء اللّهُ مَا اقْتَتَلُواْ وَلَكِنَّ اللّهَ يَفْعَلُ مَا يُرِيدُ
The explanation:
(Had God willed, then the [people] after these [apostles] would not have fought with each other, even after manifest signs [of revelation] had come to them [included in the heavenly scriptures.]
But they varied: some [steadfastly] believed and others disbelieved.
Had God willed, then they would not have fought each other,
but God does whatever He wills.)
And this aya 6: 65 is also related to this subject:
قُلْ هُوَ الْقَادِرُ عَلَى أَن يَبْعَثَ عَلَيْكُمْ عَذَابًا مِّن فَوْقِكُمْ أَوْ مِن تَحْتِ أَرْجُلِكُمْ أَوْ يَلْبِسَكُمْ شِيَعاً وَيُذِيقَ بَعْضَكُم بَأْسَ بَعْضٍ انظُرْ كَيْفَ نُصَرِّفُ الآيَاتِ لَعَلَّهُمْ يَفْقَهُونَ
The explanation:
(Say: He is All-Able to send forth upon you, [associaters,] chastisement from above you or from under your feet, or to confuse you in sects and to make you suffer of the violence of one another.
Behold [O Mohammed] how We turn about the revelations; haply that they may understand.)
And there are many other ayat with the same implication.
