First off, what is the correct spelling? Is it Koran, Quran, or Qur'an. Here are some thoughts and opinions. Apparently it doesn't matter. Pick one.
This is the primary but not the only scripture of Islam. It is the only Scripture attributed to being the exact word of Allah as given through Mohammad. The 114 chapters are called "surahs."
A key fact to remember about the Qur'an is that there are two distinctly different sets of writings. There are passages that were recorded by Mohammad in his earlier life while in the caves near Mecca. And there are passages recorded by Mohammad in his later life while in Medina. The earlier writings were written before Islam was established, in a diverse culture where Mohammads writings were neither fully understood nor embraced. Consequently, these passages have a conciliatory, neighborly, and peaceful tone. The later writings were written in a community where Islam was dominant. These passages have a warring, intolerant, supremacist tone. The rule of abrogration, a method of interpretation of both the Bible and the Qur'an, demands that the later passages supercede or cancel out the earlier passages. The intolerance and supremacist commands of these later passages are required to prevail when the situation warrants. Thus we have the dual nature of Islam, the more "peaceful" passages of the early writings, and the supremacist, warring passages of the later passages that take precedence.
Here are examples from the later, Medina revelations of Mohammad. These verses order the ardent followers to carry out endless killing of infidels/unbelievers until only Muslims remain to inhabit this Earth owned by Islamic Allah. These are a few of the many verses that take precedence over the earlier "peaceful" portions of the Qur'an. Here are some examples (courtesy of Islam Watch):
Quran 8:39: And fight them on until there is no more tumult or oppression, and there prevail justice and faith in Allah altogether and everywhere (in this earth of Allah).
Quran 9:29: Fight those who believe neither in Allah nor the Last Day, nor hold that forbidden which hath been forbidden by Allah and His Messenger, nor acknowledge the religion of Truth (Islam), even if they are of the People of the Book (Christians and Jews), until they pay the Jizya with willing submission, and feel themselves subdued.
Quran 3:85: "If anyone desires a religion other than Islam (submission to Allah), never will it be accepted of him; and in the Hereafter He will be in the ranks of those who have lost (All spiritual good)."
Quran 9:39: Unless ye go forth, (for Jihad) He will punish you with a grievous penalty, and put others in your place; but Him ye would not harm in the least. [Allah's hatred to those who are reluctant to join Islamic jihad]
Quran 9:73: O Prophet! strive hard against the unbelievers and the Hypocrites, and be firm against them. Their abode is Hell,- an evil refuge indeed.
Quran 8:65: "O Apostle! Rouse the believers to fight. If there are twenty amongst you, patient and persevering, they will vanquish two hundred; if a 100, they will vanquish a 1,000 of the unbelievers..."
Quran 8:66: "…if there are a 100 of you, patient and persevering, they will vanquish 200, and if a 1,000, they will vanquish 2,000 (two thousands) with the leave of Allah…” [This fabulous verse was written in the diary of Muhammad Ata the leader of 9/11 terrorists].
Quran 4:78: "Where ye are, death will find you, even if ye are in Towers, built up strong and tall" (Perhaps Twin towers was meant here?)
Quran 2:193: And fight them on until there is no more Tumult or oppression
Quran 2:216: Fighting is prescribed for you, and ye dislike it. But it is possible that ye dislike a thing which is good for you
Quran 5:33: The punishment of those who wage war against Allah and His Messenger, and strive with might and main for mischief through the land is: execution, or crucifixion, or the cutting off of hands and feet from opposite sides, or exile from the land: that is their disgrace in this world, and a heavy punishment is theirs in the Hereafter;
Quran 4:89: "They but wish that ye should reject Faith, as they do, and thus be on the same footing (as they): But take not friends from their ranks until they flee in the way of Allah (From what is forbidden). But if they turn renegades (change to other religions), seize them and kill them wherever ye find them; and (in any case) take no friends or helpers from their ranks;-" (Punishment for the apostates).
Quran 9:5: But when the forbidden months are past, then fight and slay the Pagans wherever ye find them, and seize them, beleaguer them, and lie in wait for them in every stratagem.
Quran 9:28: O ye who believe! Truly the Pagans are unclean; so let them not, after this year of theirs, approach the Sacred Mosque. (This verse is a glaring example how much hatreds Islam possess against non-Muslims).
Quran 8:67: "It is not fitting for an Apostle that he should have prisoners of war until He thoroughly subdued the land-." (Allah insisting Prophet to kill all the prisoners, and should not keep any surrendered prisoners alive)
Quran 8:17: It is not ye who Slew them; it is God; when thou threwest a handful of dust, it was not Thy act, but God's-.." (Allah said, the killing of surrendered soldiers were done by the wish of Allah)
Quran 9:23: "O ye who believe! Take not for protectors your fathers and your brothers if they love Infidelity above Faith: if any of you do so, they do wrong". [Quran is asking Muslims even to go against their own father and brothers in respect of religious faith]
Quran 3:28: "Let not the believers Take for friends or helpers Unbelievers rather than believers: if any do that, in nothing will there be help from Allah"
Quran 5:45: We ordained therein for them: "Life for life, eye for eye, nose for nose, ear for ear. Tooth for tooth, and wounds equal for equal." (Does this verse sound humane?)
Quran 47:4: "Therefore, when ye meet the Unbelievers (in fight), strike off their heads; at length; then when you have made wide Slaughter among them, carefully tie up the remaining captives": thereafter (is the time for) either generosity or ransom: Until the war lays down its burdens."
Quran 9:123: "Oh ye who believe! Murder those of the disbelievers and let them find harshness in you."
Quran 2:191: "Kill them wherever you find them, and drive them out from wherever they drove you out."
Quran 8:12: Remember thy Lord inspired the angels (with the message): "I am with you: give firmness to the Believers: I will instill terror into the hearts of the Unbelievers: smite ye above their necks and smite all their finger-tips off them." [Allah is really most merciful]
Other Islamic texts...
The Sunna: Comprised of the sayings of Muhammad ("hadith") and the biography or actions of Muhammad ("sirah"). In short, the Sunna contains what Mohammad said and what he did. This book is considered equal to the Qur'an in importance among Muslims. A challenge to those who consider Islam a "religion of peace" based on Islam's Scriptures: Study the life of Muhammad.