Below are four possible ways to answer this question. All of them are good opportunities to widen your listener's understanding of Islam.
1. Islam's prime directive is not to kill all non-Muslims. It is to bring all people under the rule of Sharia law. According to mainstream and accepted Islamic doctrine — accepted in all schools of Islamic jurisprudence — once non-Muslims are subjugated, they are to be given the choice between one of the following: a) converting to Islam, b) living as a subjugated, second-class citizen (a dhimmi), or c) execution. But that is after conquering non-Muslims by war.
But for many Muslims living in Western democracies, they do not believe we are in a state of open warfare yet. We are in the "pre-conquest" stage. Mohammad set the example. When he was not powerful — when Muslims were a minority in Mecca — Mohammad did not kill anyone. He focused on gaining converts. It was only when he could act from a position of strength that he began using violence. All Muslims are supposed to follow his example, according to 91 verses in the Quran. This one fact alone can fully explain the lack of universal violence among Muslims against non-Muslims.
But of course, many Muslims aren't aware of this program. The imams are fully aware of it, but many regular Muslim citizens don't know about Islam's prime directive, and at the moment, they don't need to know. It is best for Islam's ultimate goal if they just innocently go about their lives having babies and raising them to be devout Muslims.
Not many Muslims have read the Quran or understand it, partly because it has been made difficult to understand, and sometimes because many Muslims are only Muslim in name only (MINOs), or simply Muslim by birth, and they haven't taken the time to learn what they're supposed to do, and if they have, they're not interested in pursuing it.
Unfortunately, many of these apatheistic Muslims are unwitting sleeper cells. Many Muslims are secretly heterodox. They are somewhat vulnerable to recruitment, and their children are even more vulnerable to recruitment, which explains why a new study in Britain found that second generation British Muslims are more "radical" than their immigrant parents.
But for the moment, the MINOs are trying to do the one thing a Muslim must never do: Ignore the Messenger (Mohammad). So they may be perfectly nice, peaceloving people. I know three Muslims, and they are some of the nicest people I've ever met. None of them prays five times a day, and not one of them has read the Quran. I know far more about Islam than they do.
But the point is, they are three of the "millions of Muslims" who are not blowing things up. But notice this says nothing about the doctrine. They can function like sleeper cells without even knowing it. How? By simply raising each of their children to believe they are Muslims. They may not practice any of the five pillars of Islam, but they identify themselves as Muslims (apostasy is difficult, uncomfortable, and even dangerous).
So they go along with the program, and say things like, "the Quran is the perfect and final word of Allah" because they're supposed to.
Then as a teen perhaps, their child goes to a mosque (eighty percent in America preach jihad) to explore his roots a little and meets someone there who has read the Quran, who has studied it and believes in it, and he says to the kid, "do you realize your parents are hypocrites?" And what young, rebellious teen is not willing to hear that?
So the recruiter gives him a copy of the Quran and tells him to read it, and talks to him about what it really says (that he must follow its teachings or he has no chance of getting to Paradise and every chance of burning in a fiery torment forever).
Yikes! The kid reads the Quran, something he has always been told is the direct word of Allah, and that's how we end up with "homegrown jihadists" like Nidal Hasan the Fort Hood shooter, Faisal Shahzad the Times Square bomber, Umar Abdulmutallab the underwear bomber, Mujahid Muhammad the Little Rock killer, Adam Gadahn the American-born senior al-Qaeda operative, John Walker Lindh the American fighting on the side of Afghanistan, the London bombers, and on and on and on.
So yes, there are millions of Muslims who are not blowing anything up at the moment. But that does not mean we don't have a problem and we can all forget about it and go on about our business.
2. Most people have natural empathy for other people. The second most likely reason even devout Muslims may not be blowing things up is that the vast majority (probably close to 98 percent) of human beings, by and large do not like to hurt other people or even animals. It's plain ol' humanity.
So it seems likely that even some Muslims who know about this agenda choose to ignore it, and hope they can get away with it.
But even though 98 percent of people have natural human empathy, far more than 2 percent of Muslims believe in the political objectives of Islam and are actively working to achieve them, including through violence. One of the things violent cultures have always done to override this natural human empathy is to convince their believers that the enemy is not human. Mohammad called Jews, for example, "apes and pigs." Throughout the Quran, non-Muslims are depicted horribly. This indoctrination, of course, can override natural human empathy.
But for people who have not been educated in a madrassa or who had MINOs for parents and no access to a mosque, and who have not read the Quran, none of that indoctrination took place and their natural human empathy is dominant.
3. Jihad means "to strive in the way of Allah," and the striving can be done in many ways. Here are a few ways Muslims are striving in the way of Allah without physically harming anyone. Blowing things up is only one of many ways to accomplish Islam's prime directive.
Many mainstream Muslim organizations in Western democracies have decided that tactically — with some countries and in some circumstances — jihad is best waged non-violently, at least until the percentage of Muslims in the population is higher. It's a tactical decision, not a moral one. Jihad and the basic, supremacist nature of Islamic teachings have not been rejected; the violence has been postponed for strategic reasons. The strategy is to build numbers, political power, seek concessions and accommodations to Islam, and most important, disable free speech (to make it a crime to educate non-Muslims about Islam).
This is not a guess. Their purposes and strategies have been uncovered in FBI raids and the undercover infiltration of a key Islamic organization (CAIR).
4. Use Robert Spencer's standard statement. Another possible way to respond to this objection is to use the same statement Spencer uses in almost every one of his speeches: "In Islam, as in all other religions, there is a spectrum of belief, knowledge, and fervor." What it says in the doctrine does not necessarily correlate with what any particular individual will do. Enough Muslims are following the doctrine that we can't really ignore it, but that doesn't mean every single person who calls himself a Muslim is doing what Allah has commanded.
Okay, now you have four possible ways to respond to this objection. While answering, keep in mind that most people are behind the curve on jihad. They still think what we need to do is "stop the terrorists." That's only part of a much larger and far more sinister threat: The ultimate annihilation of civilizations, as was done very successfully in the first two jihads.
But I don't suggest you tell people about the annihilation of civilizations until you get them up to speed on some more basic information about Islam. If you go too far too fast in the educational process, they will mentally place you in the category of "complete nutcase" and will stop listening. Talk basics first. Let the full implications come later.
Here's another possible way to answer: Talk about ZUS zones in France.