There r different versions of answers to this question. Some say yes some say no.
I picked one of my friend's koran one day and as i read i saw where it says something like the unbeliever should be killed until the stone he hides calls out for him to be killed.
Someone should please let me know if the koran really instructed muslims to kill christians.

Kindly provide a reference to your claim, or better still re-read your friends Quran, perhaps this time you will better understand what you are reading.

[size=18pt]Aren't there some verses of the Qur'an that condone "killing the infidel"? [/size]
By Huda, About.com Guide

Question: Aren't there some verses of the Qur'an that condone "killing the infidel"?
Answer: The Qur'an commands Muslims to stick up for themselves in a defensive battle -- i.e. if an enemy army attacks, then Muslims are to fight against that army until they stop their aggression. All of the verses that speak about fighting/war in the Qur'an are in this context.
There are some specific verses that are very often "snipped" out of context, either by critics of Islam discussing "jihadism," or by misguided Muslims themselves who wish to justify their aggressive tactics.


"Slay Them" - If They Attack You First
For example, one verse (in its snipped version) reads: "slay them wherever you catch them" (Qur'an 2:191). But who is this referring to? Who are "they" that this verse discusses? The preceding and following verses give the correct context:
"Fight in the cause of God those who fight you, but do not transgress limits; for God loves not transgressors. And slay them wherever you catch them, and turn them out from where they have turned you out; for tumult and oppression are worse than slaughter, But if they cease, God is Oft-forgiving, Most Merciful, If they cease, let there be no hostility except to those who practice oppression" (2:190-193).
It is clear from the context that these verses are discussing a defensive war, when a Muslim community is attacked without reason, oppressed and prevented from practicing their faith. In these circumstances, permission is given to fight back -- but even then Muslims are instructed not to transgress limits, and to cease fighting as soon as the attacker gives up. Even in these circumstances, Muslim are only to fight directly against those who are attacking them, not innocent bystanders or non-combatants.


"Fight the Pagans" - If They Break Treaties
A similar verse can be found in chapter 9, verse 5 -- which in its snipped, out of context version could read: "fight and slay the pagans wherever ye find them, and seize them, beleaguer them, and lie in wait for them in every stratagem (of war)." Again, the preceding and following verses give the context.
This verse was revealed during a historical period when the small Muslim community had entered into treaties with neighboring tribes (Jewish, Christian, and pagan). Several of the pagan tribes had violated the terms of their treaty, secretly aiding an enemy attack against the Muslim community. The verse directly before this one instructs the Muslims to continue to honor treaties with anyone who has not since betrayed them, because fulfilling agreements is considered a righteous action. Then the verse continues, that those who have violated the terms of the treaty have declared war, so fight them, (as quoted above).

Directly after this permission to fight, the same verse continues, "but if they repent, and establish regular prayers and practice regular charity, then open the way for them, for God is Oft-forgiving, Most Merciful." The subsequent verses instruct the Muslims to grant asylum to any member of the pagan tribe/army who asks for it, and again reminds that "as long as these stand true to you, stand ye true to them: for God loves the righteous."


Conclusion
Any verse that is quoted out of context misses the whole point of the message of the Qur'an. Nowhere in the Qur'an can be found support for indiscriminate slaughter, the killing of non-combatants, or murder of innocent persons in 'payback' for another people's alleged crimes.
The Islamic teachings on this subject can be summed up in the following verses (Qur'an 60:7-:
"It may be that God will grant love (and friendship) between you and those whom ye (now) hold as enemies. For God has power (over all things), and God is Oft-Forgiving, Most Merciful.
God does not forbid you, with regard to those who fight you not for (your) faith nor drive you out of your homes, from dealing kindly and justly with them: for God loves those who are just."

http://islam.about.com/od/terrorism/f/terrorism_verse.htm

The Myth:

Muhammad only Waged War in Self-Defense

The Truth:

The myth that warfare is only justified in Islam under the condition of self-defense is disproved by the account of the Battle of Badr, in which Muhammad sent his men out to raid caravans, then deliberately provoked a battle with the Meccan army sent out to defend them. The case for aggressive warfare is also supported by the fate of the three Jewish tribes of Medina, who were cleansed because they had rejected Muhammad’s claims of prophethood (and because the Muslims wanted their possessions).

Consider the fate of the Banu Mustaliq, an Arab tribe:

"The Prophet had suddenly attacked Bani Mustaliq without warning while they were heedless and their cattle were being watered at the places of water. Their fighting men were killed and their women and children were taken as captives" (Bukhari 46:717)

Although there are many reliable accounts from the Hadith and Sira that mention the Mustaliq grazing cattle, not one mentions Muhammad making any effort at peacemaking. In this case, Muhammad's men raped the women (with his approval) after slaughtering the men (Sahih Muslim 3371). What does raping a female captive have to do with self-defense?

In many situations, Muhammad waged war for the purpose of revenge, such as the attack on the Lihyan, in which the people were clearly not prepared for war and saved themselves only by fleeing into the hills (Ibn Ishaq/Hisham 718). Muhammad also attacked the people of Taif as soon as he had the opportunity to avenge their rejection of him (Ibn Ishaq/Hisham 280 & 872).

Also disproving the myth that Muhammad only fought in self-defense is the account of his first attack on the Christians. There was no compelling reason for him to send an army to Muta (in Syria, where they met with disaster at the hands of the Byzantines). Had this been a matter of self-defense, then the enemy would surely have followed the routed army back to Arabia, but this was not the case (Ibn Ishaq/Hisham 791).

Near the end of his life, the prophet of Islam directed military campaigns for the mere purpose of spreading Islamic rule. He knew that some cities would resist and others would not. He left instructions to his people for dealing with each case:

The Messenger of Allah (may peace be upon him) said: If you come to a township (which has surrendered without a formal war) and stay therein, you have a share (that will be in the form of an award) in (the properties obtained from) it. If a township disobeys Allah and His Messenger (and actually fights against the Muslims) one-fifth of the booty seized therefrom is for Allah and His Apostle and the rest is for you. (Sahih Muslim 4346)

As can be seen, those who were not at war with the Muslims are to be subjugated anyway, and their property seized. The only distinguishing factor is the extent of Muslim entitlement following the victory.

Military campaigns to extend Islamic domination include the raid on Tabuk, which was a second incursion into the Christian territory of Syria, in which Muhammad forced the local populace to pay him tribute after ambushing and killing local civilians to assert his authority (Ibn Ishaq/Hisham 903). Another example would be the “convert or die” mandate given to an Arab tribe, the Banu al-Harith:

Then the apostle sent Khalid bin Walid… to the Banu al-Harith and ordered him to invite them to Islam three days before he attacked them. If they accepted then he was to accept it from them, and if they declined he was to fight them. So Khalid set out and came to them, and sent out riders in all directions inviting the people to Islam, saying, “If you accept Islam you will be safe.” So the men accepted Islam as they were invited. (Ibn Ishaq/Hisham 959)

Obviously self-defense was not a factor in any of these cases (even though some Muslims are prone to embellish the record with imaginary details not found therein). As with the capture of Mecca in 630, these early Muslims had clear military superiority and the target of their aggression was in no position to defend itself.

In fact, the first part of the 9th Sura, the most bellicose chapter of the Qur’an, was revealed shortly after the Muslims had established military dominance in Mecca. Consider one of the more violent verses:

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 (of war); but if they repent, and establish regular prayers and practice regular charity, then open the way for them (9:5)

The words, “when the forbidden months are past,” precludes the possibility that this was a matter of self-defense. The Muslims had already been given the divine right to fight during the sacred months, and it is simply implausible that they would have suffered attacks over a four month period without defending themselves. That they were not under attack is consistent with the historical context, in which the Haj period was a traditional time of peace and tolerance throughout Arabia.

Although not under attack from the pagans, Muhammad ordered his men to chase and kill the unbelievers following the Haj. The pagans who agreed to become Muslim (ie. practice the pillars of Islam, zakat and salat) would be allowed to live following their conversion. Verse 9:29 offers a separate rule for Jews and Christians, allowing them to keep their religion as long as they pay protection money to Muslims and acknowledge the inferiority of their faith. Should they resist, then they should be killed.

One of the best documented examples of Muslim aggression during the lifetime of Muhammad is the attack on the peaceful community of Khaybar. This followed the treaty of Hudaibiya between the Muslims and Meccans, which called for a period of peace between the two groups. The treaty was controversial with Muslims, not only because it contradicted Allah’s prior mandate to “drive out” the Meccans with violent force (2:191), but also because Muhammad agreed not to be recognized as a prophet in the document (Muslim 4401).

Muhammad decided that it was prudent to attack the Jews at Khaybar in order to regain the trust of his people and placate their grumbling with military victory and (especially) the stolen wealth that followed. This is embarrassing to modern-day Muslim apologists, who try to justify the siege by imagining that the sleepy farming community, located about 100 miles outside of Medina, posed some sort of necessary threat.

Unfortunately for contemporary apologists, not only is there no supporting evidence that the Muslims were under attack by the Khaybar, there are at least three historical references that flatly contradict any notion of self-defense on the part of Muhammad. The first is a description of the initial attack by Ibn Ishaq/Hisham:

We met the workers of Khaybar coming out in the morning with their spades and baskets. When they saw the apostle and the army they cried, “Muhammad with his force,” and turned tail and fled… The apostle seized the property piece by piece… (Ibn Ishaq/Hisham 757)

The people of Khaybar were not attacking Muhammad. They were farming their land with shovels and buckets, not even knowing that they were supposed to be at war. This is further confirmed in the same text:

When the apostle raided a people he waited until the morning. If he heard a call to prayer he held back; if he did not hear it he attacked. We came to Khaybar by night, and the apostle passed the night there; and when morning came he did not hear the call to prayer, so he rode and we rode with him. (Ibn Ishaq/Hisham 757)

Muhammad attacked only after waiting to see if the people of Khaybar issued a morning call to prayer. This would have no possible relevance had they already been at war with him.

Perhaps the best proof that Muhammad was not acting in self-defense is the fact that his own people did not understand why they were marching to war. His son-in-law, who was in charge of the military expedition, had to ask for justification:

Allah's Messenger called Ali [and said]: “Proceed on and do not look about until Allah grants you victory,” and Ali went a bit and then halted and did not look about and then said in a loud voice: “Allah's Messenger, on what issue should I fight with the people?” Thereupon he (the Prophet) said: ”Fight with them until they bear testimony to the fact that there is no god but Allah and Muhammad is his Messenger…” (Sahih Muslim 5917)

The question Ali posed would have been unnecessary had the Muslims been under attack by the Khaybar or if the answer to the question were obvious. As it is, Muhammad’s reply underscores the ostensible purpose of the campaign, which was to force the Jews into acknowledging the superiority of Islam.

Muhammad’s men easily captured Khaybar and divided up the loot. The prophet of Islam tortured the community’s treasurer to extract information, then had him killed (Ibn Ishaq/Hisham 764). Muhammad then took the man’s widow, Saffiya, as his wife after trading two other captured women to one of his lieutenants (Ibn Ishaq/Hisham 758). The surviving Jews were allowed to stay on their land provided that they gave their Muslim masters an ample share of their crops.

Therefore, the rule of aggression in Islam, from the example set by Muhammad, is that it is proportional to the power held by Muslims, and not the persecution that they are under. The rare verses of peace in the Qur'an were "revealed" in Mecca, when true oppression existed (in some cases). The verses of violence that are revealed later correspond to Muslim military might even as any persecution of Muslims had largely dried up.

Any verse that is quoted out of context misses the whole point of the message of the Qur'an. Nowhere in the Qur'an can be found support for indiscriminate slaughter, the killing of non-combatants, or murder of innocent persons in 'payback' for another people's alleged crimes.
The Islamic teachings on this subject can be summed up in the following verses (Qur'an 60:7-:
"It may be that God will grant love (and friendship) between you and those whom ye (now) hold as enemies. For God has power (over all things), and God is Oft-Forgiving, Most Merciful.
God does not forbid you, with regard to those who fight you not for (your) faith nor drive you out of your homes, from dealing kindly and justly with them: for God loves those who are just."

I see frosbel has debunked your conclusion.

The topic should be "Does The Koran Really Encourage Faithful Moslems To Kill non believers?"

Wooow all good muslim must kill an thouse that are not killing are not good muslim that why boko haram are killing them the moderate ones