I agree with Dinesh, but wanted to add my own thoughts as to why his words ring so true. To understand where my post is coming from, let's start with the general left/right paradigm, or at least one way of looking at such things:
autonomy / anarchy <-----------------------------> authority / law & order
To the liberal, "tolerance" really stems from a desire for complete autonomy. Autonomy literally means "self law," where everyone gets to do whatever makes them happy. (This is also why this group is so often accused of being driven by their emotions, and having such strong emotional reactions to things that upset them / make them unhappy.) Not surprisingly, the left's ideal is a Utopian society where everyone lives in blissful peace; but their reality is a society where complete anarchy would result, because everyone would eventually do whatever made them happy. That's the far left. Marxism, Communism, Socialism, and all forms of the "Sexual Revolution" fall into that category. That's why those groups all get along under the guise of "tolerance." I'll get to Radical Islam in a moment.
On the other side of the spectrum, you have those who value absolute authority and the resulting law & order. Christians value the authority of the Word of God and the government, so long as the latter is not acting contrary to the Word of God and/or the Constitution, subject to the caveats listed below. Non-Christian conservatives generally also value the authority of the Constitution and government, so long as the latter is acting in accordance with the Constitution as originally written and properly amended (so, e.g., no inherent "right to privacy" leading to abortion, or other forms of judicial activism and "legislating from the bench").
Because the political left wants complete autonomy, they hate those who push for complete authority and law & order. And for that reason, the left has no "tolerance" for those who value absolute authority and law & order, namely the Christians and the other conservatives. To "tolerate" such groups would go against their true underlying motivations for complete, emotion-driven self-governing autonomy.
Islam is a unique bird. From the perspective of Islam itself, Islam is as far to the right as you can get. They lack the grace and mercy and love of Christianity, so they value an absolute authority that has NO FORGIVENESS. If you look at it from their own perspective, and look at what they really believe as laid out in the Quran, Hadidth, and Shariah, then you see that Islam (all of Islam, not just "Radical" Islam) is as far to the right as you can possibly get. In fact, Islam is further to the right than even Christians or the most adamant conservatives.
But from the perspective of the left, most of whom generally don't know what Islam actually stands for or is about, they see Islam as just another "oppressed minority" who wants their own absolute freedom (autonomy) to do whatever they want. And so for now, the left both accepts and embraces Islam as one of their own. But what they fail to realize is that Islam is the ultimate Trojan Horse. As Islamic leadership has said time and again, they plan to use America's religious liberty laws against America, to actually use our own laws and protections to eventually overthrow those very laws and protections. The plan is to hide behind the protection of these laws as long as they lack political power, and then to eventually overturn these laws and impose the Sharia once they get sufficient political power.
Now some may say, "Well, wait, Islam is only 2.1% of the country right now -- that's far from a political majority!" To which I'd respond, the Muslim population in America has more than doubled in the last 15 years, and shows no sign of slowing down. It's not hard to imagine the Muslim population being around 4-5% of the total U.S. population in another 10-15 years.
Now again, some may say, "Well, wait, 4-5% of the population is hardly a majority!" Yes, but that's still plenty big enough to wield political power and begin to destabilize society, especially when they begin to form political alliances with the left, a group who will offer sympathy for their "plight." If you don't believe that, you need look no further than the LGBT community in America. The American LGBT community is only around 3-4% of the population, but yet look at the political power that it already wields. Once the Muslim population roughly doubles again, in another 10-15 years, they'll be at the same level as the LGBT community today -- and we already see the groundswell of support from the left for their "cause." If we continue down this path, we'll be at the point of no return before we realize what happened. Once they have sufficient numbers within their community -- and sufficient sympathy and allegiances from other political communities --they will begin imposing their political will on the same "tolerant" society that once celebrated their arrival.
If we don't reverse the ship now, we are setting this country on an irreversible course to complete anarchy and destruction, potentially within our lifetimes. And if this country falls, as the last major beacon of the Christian West, I believe the world will fall with it.
"For I did not shrink from declaring to you the whole counsel of God." (Acts 20:27)