At the core of Islam's theology is the belief that Allah is the only god and he is the creator of Universe and every thing in it. In Koran, Allah says he created mankind for a purpose and the purpose is that they serve him by worshiping him alone. See the following verse:
051.056,YUSUF ALI: I have only created Jinns and men, that they may serve Me.
PICKTHAL: I created the jinn and humankind only that they might worship Me.
SHAKIR: And I have not created the jinn and the men except that they should serve Me.
The Muslims believe and say that Allah sent guidance, Koran, to the entire mankind through Mohammad (34:028) and Koran contains code (laws) for every thing in life, complete way of life and with in these laws that humans should conduct their affairs and live. So Koran is Allah's will and by following Koran Muslims submit to Allah and it is the only path for Mankind to achieve felicity in afterlife and other paths (faiths) only leads to Hell fire. So far so good. But the problem is Koran doesn't stop here.
It makes an obligation on Muslims to spread this message to the mankind (16:125-128) and to strive to make law based on Koran as dominant one through out the world. If disbelievers on hearing this this guidance from Allah (Koran) do not convert to Islam, it is a grave offence in the eyes of Allah. So what does Koran say about such people? Much broader and better question is what is the Koranic view of other faiths and their believers? It is vital and important to know this to understand Islam. We have seen this question in some posts and we also have seen some answers like Non Muslims are inferior, their bestial like status and Non Muslims are fuel for fire. It also says that Non Muslims are followers of Shaitan and their faiths are nothing but seditions and influences of Shaitan and are not worthy to exist (009:033, 61:09 and 48:28). Much worse is that Allah prevents disbelievers from understanding, so he could punish them in Hell. One of the cardinal verse among many is excoriating disbelievers as deaf and blind because they refused Islam. Just read the following verses.
25:055, HILALI: And they (disbelievers, polytheists, etc.) worship besides Allah, that which can neither profit them nor harm them, and the disbeliever is ever a helper (of the Satan) against his Lord.
006.043,YUSUF ALI: When the suffering reached them from us, why then did they not learn humility? On the contrary their hearts became hardened, and Satan made their (sinful) acts seem alluring to them.
019.083,YUSUF ALI: Seest thou not that We have set the Evil Ones (Shaitan is the actual word) on against the unbelievers, to incite them with fury?
SHAKIR: Do you not see that We have sent the Shaitans against the unbelievers, inciting them by incitement?
043.036,SHAKIR: And whoever turns himself away from the remembrance of the Beneficent Allah, We appoint for him a Shaitan, so he becomes his associate.
010.100,YUSUF ALI: No soul can believe, except by the will of Allah, and He will place doubt (or obscurity) on those who will not understand.
032.013,YUSUF ALI: If We had so willed, We could certainly have brought every soul its true guidance: but the Word from Me will come true, "I will fill Hell with Jinns and men all together."
018.057,YUSUF ALI: And who doth more wrong than one who is reminded of the Signs of his Lord, but turns away from them, forgetting the (deeds) which his hands have sent forth? Verily We have set veils over their hearts lest they should understand this, and over their ears, deafness, if thou callest them to guidance, even then will they never accept guidance.
017:045,SHAKIR: And when you recite the Quran, We place between you and those who do not believe in the hereafter a hidden barrier;
017.046,YUSUF ALI: And We put coverings over their hearts (and minds) lest they should understand the Qur'an, and deafness into their ears: when thou dost commemorate thy Lord and Him alone in the Qur'an, they turn on their backs, fleeing (from the Truth).
045.023,SHAKIR: Have you then considered him who takes his low desire for his god, and Allah has made him err having knowledge and has set a seal upon his ear and his heart and put a covering upon his eye. Who can then guide him after Allah? Will you not then be mindful?
036.007,008,009,010:SHAKIR: Certainly the word has proved true of most of them, so they do not believe. Surely We have placed chains on their necks, and these reach up to their chins, so they have their heads raised aloft. And We have made before them a barrier and a barrier behind them, then We have covered them over so that they do not see. And it is alike to them whether you warn them or warn them not: they do not believe.
002.006,007:YUSUF ALI: As to those who reject Faith, it is the same to them whether thou warn them or do not warn them; they will not believe. Allah hath set a seal on their hearts and on their hearing, and on their eyes is a veil; great is the penalty they (incur).
006:039:SHAKIR: And they who reject Our communications are deaf and dumb, in utter darkness; whom Allah pleases He causes to err and whom He pleases He puts on the right way.
016.093:SHAKIR: And if Allah please He would certainly make you a single nation, but He causes to err whom He pleases and guides whom He pleases; and most certainly you will be questioned as to what you did.
028.056:YUSUF ALI: It is true thou wilt not be able to guide every one, whom thou lovest; but Allah guides those whom He will and He knows best those who receive guidance.
004.143,YUSUF ALI: (They are) distracted in mind even in the midst of it,- being (sincerely) for neither one group nor for another whom Allah leaves straying,- never wilt thou find for him the way.
027.004:YUSUF ALI: As to those who believe not in the Hereafter, We have made their deeds pleasing in their eyes; and so they wander about in distraction.
039.023:YUSUF ALI: Allah has revealed (from time to time) the most beautiful Message in the form of a Book, consistent with itself, (yet) repeating (its teaching in various aspects): the skins of those who fear their Lord tremble thereat; then their skins and their hearts do soften to the celebration of Allah's praises. Such is the guidance of Allah: He guides therewith whom He pleases, but such as Allah leaves to stray, can have none to guide.
035.008:SHAKIR: What! is he whose evil deed is made fairseeming to him so much so that he considers it good? Now surely Allah makes err whom He pleases and guides aright whom He pleases, so let not your soul waste away in grief for them; surely Allah is Cognizant of what they do.
016.028,029,030:YUSUF ALI: "(Namely) those whose lives the angels take in a state of wrong-doing to their own souls." Then would they offer submission (with the pretence), "We did no evil (knowingly)." (The angels will reply), "Nay, but verily Allah knoweth all that ye did; "So enter the gates of Hell, to dwell therein. Thus evil indeed is the abode of the arrogant." To the righteous (when) it is said, "What is it that your Lord has revealed?" they say, "All that is good." To those who do good, there is good in this world, and the Home of the Hereafter is even better and excellent indeed is the Home of the righteous,-
046.026,YUSUF ALI: And We had firmly established them in a (prosperity and) power which We have not given to you (ye Quraish!) and We had endowed them with (faculties of) hearing, seeing, heart and intellect: but of no profit to them were their (faculties of) hearing, sight, and heart and intellect, when they went on rejecting the Signs of Allah; and they were (completely) encircled by that which they used to mock at!
021.045,YUSUF ALI: Say, "I do but warn you according to revelation": But the deaf will not hear the call, (even) when they are warned!
010:100,SHAKIR: And it is not for a soul to believe except by Allah's permission; and He casts uncleanness on those who will not understand
Now lets construct a small parable for our self to understand Allah and his view point: how would one feel if a party wins the elections and forms a Government. Now after forming the Govt. suppose it starts persecuting and killing people who did not vote for it or agreeing with it over policies. How should this be seen? Now considering that we expect Almighty to be more merciful and kind, can Koran be a word of God? May be but then that God must be one cruel one and tyrant and definitely not worth worshiping.