Monsignor Charles Pope, over at the Archdiocese of Washington has written cogently on the subject of "Tolerance" here.
I am about toleranced out here in Canada, as tolerance is being defined by the well meaning but left leaning wingnuts, and as I spend many months of the year in the US, can see that it is also becoming a serious problem in America. In my view, Monsignor Pope is ahead of the curve in the US, and about a decade late for those of us here in Canada, who have to tolerate more wing nuttery than you can shake a stick at.
In case the words are too big for you, the good Monsignor had a youTube video from Theater of the Word Inc. at the end of his commentary, and I have linked it below as well. It summarises the situation.
Permit me a few thoughts on the issue of tolerance. This post is not intended as a systematic treatise on tolerance. Rather just some thoughts on a frequently misunderstood concept that some have called the only “virtue” left in our neo-pagan society.
The Stanford Encyclopedia of Philosophy defines Tolerance and toleration:
Toleration — from the Latin tolerare: to put up with, countenance or suffer — generally refers to the conditional acceptance of or non-interference with beliefs, actions or practices that one considers to be wrong but still “tolerable,” such that they should not be prohibited or constrained. 
It goes on to make a distinction that is often lost today:
[I]t is essential for the concept of toleration that the tolerated beliefs or practices are considered to be objectionable and in an important sense wrong or bad. If this objection component (cf. King 1976, 44-54) is missing, we do not speak of “toleration” but of “indifference” or “affirmation.” 
In effect tolerance involves putting up with something we consider wrong or displeasing but not so wrong that we must move to constrain it. Tolerance does NOT mean we approve of something as good. This essential point is often glossed over by those who often demand that tolerance mean approval, and that to disapprove of something makes one “intolerant.”
Of itself, tolerance is a good and necessary thing. But, like most good things, it has its limits. As a good thing, tolerance is essential in an imperfect world. Without tolerance we might go to war over simple human imperfections. We all have friends and family members who are people we like but, as with every human person, they also have annoying or less desirable traits. Without tolerance we would be locked in a power struggle and a fruitless battle to make each person perfect to us. As it is we tolerate less desirable aspects of people for higher goods such as harmony, friendship, respect, mercy, kindness and the like.
However, there are limits to tolerance. There are just some things in human relationships that are “deal breakers.” There are things that cannot be tolerated. For example serious and persistent lies breach the trust necessary for relationships and such behavior is not tolerated reasonably. Behavior that endangers one or both parties (either physically or spiritually) ought not be tolerated and often makes it necessary to end relationships or establish firm boundaries.
In wider society tolerance is also necessary and good but has limits. For example we appreciate the freedom to come and go as we please and it is good to tolerate the comings and goings of others. This is so even if some of the places they go, (e.g. a brothel), do not please us or win our approval. Without such a general tolerance of movement things would literally grind to a halt. But for the sake of the value of coming and going freely we put up with the less desirable aspects of it. However this tolerance has its limits. We do not permit people to drive on sidewalks, run red lights or drive in the left lane of a two way street. Neither do we permit breaking and entering or the violation of legitimate property rights. We restrict unaccompanied minors from certain locales, etc. In effect, every just law enshrines some limit to tolerance. Conservative and Liberals debate what limits law should enshrine but both sides want civil law to set some limits. Even Libertarians, while wanting less law, see a role for some law and limits, for they are not anarchists.
So, toleration is a good and necessary thing but it has its limits. Our modern struggle with the issue of tolerance seems to be twofold:
1.The definition of tolerance, as we have discussed, is flawed. Many people equate tolerance with approval and many call disapproval, intolerance. But, as we have seen this is flawed. Without some degree of disapproval, tolerance is not possible.
2.The second problem centers around the limits of tolerance. In our modern world we are being asked to tolerate increasingly troublesome behavior. A lot of this behavior centers around sexual matters. Proponents of sexual promiscuity demand increasing tolerance despite the fact that their behavior leads to diseases, abortion, teenage pregnancy, single parent families, sexual temptation, divorce, and all the ills that go with a declining family structure. Abortion proponents also demand tolerance of what they advocate although this behavior results in the death of an innocent human beings. Many people of faith think that the limits of tolerance have been transgressed in matters such as these.
Rapprochement? - The debate about toleration and its limits is not new but it seems more intense today when a shared moral vision has largely departed. Perhaps we cannot as easily define the limits of tolerance today but one way forward might be to return to a proper definition of tolerance. Perhaps if we stop (incorrectly) equating tolerance with approval a greater respect will be instilled in these debates. To ask for tolerance is not always wrong, but to demand approval is.
Consider the debate over homosexual activity. Many people of faith, at least those who hold to a more strictly Biblical view, find homosexual behavior to be wrong. The same can be said for illicit heterosexual behavior such as fornication, polygamy, and incest. But on account of our disapproval of homosexual behavior we are often called “intolerant,” (and many other things as well such as homophobic, bigoted, hateful, etc).
But tolerance is really not the issue. Most Christians are willing to tolerate the fact the people “do things in their bedroom” of which we disapprove. As long as we are not directly confronted with private behavior and told to approve of it we are generally willing to stay out of people’s private lives. But what has happened in modern times is that approval is demanded for behavior we find objectionable. When we cannot supply such approval we are called intolerant. This is a misuse of the term.
And further, what if our objections do simply emerge from bigotry as some claim but, rather, from a principled biblical stance? Our disapproval does not, ipso facto, make us bigots. Neither does it mean we are wholly intolerant and seek to force an end to behavior we do not consider good. Very few Christians I have ever heard from are asking for the police to patrol streets and enter bedrooms and make arrests. We are not intolerant, we simply do not approve of homosexual activity. And, according to the proper definition of tolerance, it is the very fact of our disapproval, that permits us to show forth tolerance. Perhaps such a consideration might instill greater respect in these debates and less name-calling from our opponents.
An aside- Gay “marriage” is a more complicated matter since it involves existing law and a demanded change in that law by proponents of so-called “gay marriage.” Most traditional Christians see a limit to tolerance here since we consider that God defined and established marriage as described in Genesis 1 & 2. Hence we cannot favor attempts to substitute a human redefinition of something we believe instituted by God.
Finally a thought as to who really “owns” tolerance. Opponents of traditional Christians often claim the high ground of tolerance for themselves. But the paradoxical result of this is a holier-than-thou attitude and an increasing intolerance of Christian faith by the self-claimed tolerant ones. Legal restrictions of the proclamation of the Christian faith in the public square are increasing. Financial exclusion of Catholic Charities from Government money used in serving the poor are becoming more common as well. In other parts of the world where free speech is less enshrined, Catholic priests and bishops are being sued and even arrested for “hate speech” because they preach traditional biblical morality. None of this sounds very tolerant. Our opponents need not approve of our beliefs but they ought to exhibit greater tolerance of us, the same tolerance they ask of us.