Is there a causal connection between religion and the use of force? Yes. In that connection, is there a significant difference between Christianity and Islam? Yes--but it lies in the distinction, not between the Bible and the Koran, but between today's Christians and Muslims.
In the Medieval era, when the authority of the Church was virtually unquestioned, those who questioned it were put to death. The Church recognized no freedom of thought--it recognized no concept of freedom as such. Freedom is a state of personal autonomy, in which the decisions about which ideas to accept and which actions to take are made by each individual, without outside coercion. The underlying premise is that everyone is entitled to his own life and to the pursuit of his own happiness. This, however, was anathema to the Church, which held that the individual has no autonomy--that he has no right to arrogate to himself the decision of how to lead his life--that he exists only to serve God, who has full dominion over his life. The Bible demands that blasphemers be killed, and the Church readily complied, using such tools as the Crusades and the Inquisition to wage a Christian Holy War against the faithless.
Because freedom essentially means freedom of the mind, people lose their freedom whenever religion holds political power. Religion demands the surrender of the intellect. It orders you to subordinate reason to faith, and to yield to an authority higher than your independent mind. It orders you to act not on what you understand, but on what others tell you to believe. Instead of the freedom to think, there is only the duty to obey and to serve God. And a servant who defies his master's commands must be compelled to submit. So medieval heretics were burned at the stake for the glory of God--an act akin to the machine-gunning of infidels to the chants of "Allahu akbar."
Only with the flowering of the Renaissance and then the Enlightenment did the Church's authority wane. Reason came to be elevated above mindless dogmas, a development that affected all institutions of the West, even religion. Reason was allowed to temper the worst irrationalities of faith, and religious dissent came to be tolerated. The Biblical commandments to kill blasphemers--and witches and homosexuals and violators of the Sabbath--were no longer taken seriously. In time, political freedom took root. The United States was founded, and church was separated from state.
But the Islamic world did not go through an Enlightenment. That world still clings to its dogmas the way it did many centuries ago. This is the central fact distinguishing Muslims from Christians. The Koran is taken more seriously and more literally by its followers than is the Bible by its followers. In the West, even the religious retain a certain respect for reason. They generally understand that religion should be a private, not political, concern (though that understanding has been unfortunately weakening). They would oppose, say, making the Bible America's official Constitution--as the Koran is officially Saudi Arabia's.
What about the so-called moderate Muslims? They exist, but let's first define that term. It cannot refer merely to those who refrain from beheading infidels. In today's context, there is a simple way to distinguish a moderate Muslim: he is someone who acknowledges the categorical right to repudiate Islam. And as a logical corollary, he regards Osama bin Laden and his ilk as monsters who deserve to be executed. The crucial point is that he disavows the essence of jihadism: the idea that Islam is to be imposed by force.
But in the Muslim world such disavowers are the exception. Look at the governments of Muslim nations. In Egypt, Kuwait, Pakistan, Algeria, Afghanistan, Saudi Arabia and Iran, blasphemers are put to death. (Other Muslim countries impose prison sentences.) In Saudi Arabia, the law defines as terrorists all atheists and anyone "calling into question the fundamentals of the Islamic religion on which this country is based." What are such policies if not legalized jihadism--that is, the forcible imposition of Islam upon unwilling victims, simply done under the sanction of law?
And these policies have strong popular support. In the famous Pew poll of 2013, which asked Muslims whether apostates should be put to death, a majority of respondents in Egypt, Jordan, Afghanistan, Pakistan and the Palestinian territories said yes.
We see numerous protests in the name of Islam against critics of Islam--where are the protests in the name of Islam against the savage killers of the critics? The religious leaders of Islam readily issue fatwas against the ridiculers of Muhammed--where are the fatwas against the people who abduct schoolchildren, firebomb synagogues, make sex-slaves of girls, decapitate journalists and otherwise fail to practice a "religion of peace"?
America's enemies are those who seek to institute Islamic totalitarianism--and those who support them. People should be free to pray to Allah and praise the Koran. But if they act to abet the users of force in any way, they then become "immoderate" Muslims.
Philosophically, one can show that the demands of religion are incompatible with the principle of freedom. Philosophically, one can show that when reason is replaced by faith, disagreements can be dealt with only by brute force. Philosophically, one can show that the jihadists are consistently implementing the dictates of Islam. But politically--i.e., with respect to the action that government should take-- it does not matter whether they are practicing a "true" or a "false" religion. What matters is that millions of Muslims accept the ideology of Islamic totalitarianism and that it is a demonstrable threat to us. Perhaps President Obama would wish to call it pseudo-Islamic totalitarianism. Nonetheless, it remains the ideology of the people who want to impose their religion--whether "true" or "false"--on the rest of us by force. The followers of that ideology, from the aggressive beheaders to the milder abettors, are the enemy--and our government must stop them.