"If God be for us, who can be against us?" Rom. 8:31
It is well-known that the spread of religious ideas has often been facilitated by the threat of force. Economic, social, political, or physical force (violence) has been exercised by and upon nearly every religion in history. In the name of God, our ancestors exterminated entire communities and even cultures, using scripture and traditional doctrine as justification.
To be fair, the forceful propagation of religion carried with it certain economic, strategic, or political incentives. The church has classically endorsed or encouraged actions that strengthen its position in the world. The same could be said of certain political ideologies (Communism or Socialism, for example) that hold secular philosophy in high regard. However, it is not these additional considerations that concern me. What concerns me is that each of the three largest religions today have scripture that not only permits this, but encourages it.
It is truly appalling that these attitudes prevail to this day. Muslim, Jewish, and even Christian extremists routinely call for, attempt, or rejoice in the extermination of those who do not subscribe to their preferred dogma. While Muslim extremists have the dubious distinction of having carried out the most recent and egregious acts of religious terrorism, the scripture for each of the aforementioned faiths contain similar exhortations to cast out, cut off, and even kill non-believers.
Christians are quick to argue that their faith does not sanction this type of behavior. Yet in reality this is due to the influence of increasingly rational thought and liberal philosophy, not scripture. The OT does in fact contain a call to kill unbelievers that is nearly identical to the Qur'an.
The Qur'an advocates or implies the killing and/or punishment of unbelievers in several places. However, for the sake of simplicity (many of the verses are more spread out) and contextual comparison we'll look at just one.
In verse 89 of Chapter 4: AN-NISA(WOMEN), the text reads (using the Shakir translation):
"They desire that you should disbelieve as they have disbelieved, so that you might be (all) alike; therefore take not from among them friends until they fly (their homes) in Allah's way; but if they turn back, then seize them and kill them wherever you find them, and take not from among them a friend or a helper."
In comparison, here's a look at Deut. 13:5-16:
"5 And that prophet, or that dreamer of dreams, shall be put to death; because he hath spoken to turn you away from the LORD your God, which brought you out of the land of Egypt, and redeemed you out of the house of bondage, to thrust thee out of the way which the LORD thy God commanded thee to walk in. So shalt thou put the evil away from the midst of thee. 6 If thy brother, the son of thy mother, or thy son, or thy daughter, or the wife of thy bosom, or thy friend, which is as thine own soul, entice thee secretly, saying, Let us go and serve other gods, which thou hast not known, thou, nor thy fathers; 7 Namely, of the gods of the people which are round about you, nigh unto thee, or far off from thee, from the one end of the earth even unto the other end of the earth; 8 Thou shalt not consent unto him, nor hearken unto him; neither shall thine eye pity him, neither shalt thou spare, neither shalt thou conceal him: 9 But thou shalt surely kill him; thine hand shall be first upon him to put him to death, and afterwards the hand of all the people. 10 And thou shalt stone him with stones, that he die; because he hath sought to thrust thee away from the LORD thy God, which brought thee out of the land of Egypt, from the house of bondage. 11 And all Israel shall hear, and fear, and shall do no more any such wickedness as this is among you. 12 If thou shalt hear say in one of thy cities, which the LORD thy God hath given thee to dwell there, saying, 13 Certain men, the children of Belial, are gone out from among you, and have withdrawn the inhabitants of their city, saying, Let us go and serve other gods, which ye have not known; 14 Then shalt thou enquire, and make search, and ask diligently; and, behold, if it be truth, and the thing certain, that such abomination is wrought among you; 15 Thou shalt surely smite the inhabitants of that city with the edge of the sword, destroying it utterly, and all that is therein, and the cattle thereof, with the edge of the sword. 16 And thou shalt gather all the spoil of it into the midst of the street thereof, and shalt burn with fire the city, and all the spoil thereof every whit, for the LORD thy God: and it shall be an heap for ever; it shall not be built again."
As the reader can plainly see the Bible does order the killing of unbelievers in much the same way as the Qur'an. The former text is simply more to the point (i.e., shorter). In addition, the Bible advocates the destruction of an entire city because of the presence of 'certain men' (those of a competing faith, but also applies to non-believers).
One interesting note is that the Qur'an seemingly gives the unbeliever a chance. If the unbeliever decides to "fly in Allah's way" (follow the faith or become a believer), he/she can avoid death. Of course, this does not mean that this passage is to be embraced, but it is notable in that no such chance is given to the unbelievers in the biblical text.
A Christian might easily retort that Jesus nullified this and all other OT Laws through the atonement. Verses such as Matt 5:38-48 and Luke 6:27-36 do seem to indicate that Jesus held a different view. However, in light of Jesus' less charitable sayings such as Luke 12:49-53, Luke 14:26-27, and Matt 10:21-22, 34-39, combined with Jesus' famous affirmation of OT Law in Matt 5:18, is this at all certain?
Of course, this topic also hints at the contradiction between the prohibition against murder (Ex 20:13) and the legislation of death for transgressors and non-believers to be found in Leviticus and Deuteronomy. Then again, in the days in which the Bible was written perhaps such things weren't considered murder, but that's a topic for another time.
In any case, while we are fortunate that rational thought and the application of liberal theology has resulted in a more palatable version of Christianity than might have been, no Christian can claim his/her faith is any more based on tolerance or peace than Islam. The violent intolerance displayed in the OT is something Christians do well do discard, but cannot deny is indeed commanded by God in scripture.