"Toleration" is one confused mess of an intellectual concept and social ideal nowadays. In different ways, it always has been. No one really knows when it's good, when it's bad, or even what it is. But in many respects it is a noble social goal, and thus it's a concept and ideal worth understanding.
To begin with, and generally speaking: Everyone's different. Every human being is born naturally different and ineluctably divergent from his fellows; and we tend to become more so over time. But we still all need to get along, and interact successfully and profitably. So we all need to accept and "tolerate" these inborn, inherent, inevitable, undeniable differences between us. And we similarly need to tolerate many of the acquired and freely-chosen differences between us as well.
The great social desideratum seems to be this: Everyone should tolerate all natural (genetic) differences in others, which presumably can't be evil; and all nurtural (environmental) differences in others which are morally good, or at least neutral. But no one should tolerate self-created or socially-imposed evils in another person, especially those which are fundamental or important. The basic rule is: Human variety is acceptable, human immorality is not.
In a real sense, no natural, genetic, inherent, inborn evils exist or even can exist. There's no such thing as Original Sin. Mother Nature, in general, doesn't err. Or at least not among socializing human beings because -- biologically and anthropologically speaking -- no true parasite-host or predator-prey relationship ever obtains. No matter how different one human being is from another, when it comes to minimally intelligent and psychologically sound adults, our normal, natural (healthy, happy) relationship and interaction never involves fundamental physical rivalry or bodily threats. Thus no animal-like "competition" or "territoriality" ever comes in to play.
Still, in seeking rational, just, benevolent, friendly, social toleration one must realize and admit that people tend to be quite different. This is so despite the American Revolution's claim that "all men are created equal" and the French Revolution's great ideal of universal human "equality." Both claims were and are important but very general truths of loose, high-minded social ambiguity. They're also a bit of empty, unexplainable, intellectual drivel.
The Romans probably understood this issue best. They saw all mankind as equal "in essence" but not in natural abilities, developed skills, or freely-chosen character and integrity. Rome was truly and admirably "multi-cultural" in that it encompased a wide variety of sub-races and races without prejudice. But this Roman knowledge and virtue is now lost to us.
The reality here is that the only solid, sure, real, definite human equality, or proper ideal thereof, is political. In every other respect -- including intelligence, morality, wealth, education, creativity, sociability, adaptability, tolerance, athleticism, libido, pulchritude, etc. -- human beings are born, live, die, and forever stay wildly different. And yet...once a normal-type human being with an IQ of 100 or so becomes physically and mentally adult, he does seem to be existentially equal, and thus deserve to be treated by his fellows with absolute equality before the government and under the law.
This continues to be true even tho' human variation in many respects seems quite profound. This differentiation seems to be especially pronounced for men and women. And for whites, blacks, and yellows. And for hetero's and homo's.
And this is particularly so physically, mentally, and psycho-spiritually. No less than 12 separate human archetypes exist and they possess no less than 36 separate fundamental characteristics.
And all these natural and biological differences are generally significantly augmented and exacerbated by their subgroup's nurture or culture in a naturally reinforcing feedback loop. The racial version of this, prior to WWII, was known as "national character." Back then, everyone knew that the French and English and Germans were different. But Hitler poisoned this concept, along with the ideals of eugenics. Thus this knowledge and wisdom is also lost to us.
But this notable "diversity" enhancement or seeming social "atomization" -- which is so scary to "progressives" and "democrats" today -- is actually usually moderately to the good of the community. And to the whole of humanity. Race, sex, and sexuality egalitarians need to rethink their ideas and ideals here. Procrusteanism isn't a limitless virtue.
Now...few people in today's maliciously fatuous and wantonly "politically correct" era want to understand or admit this but: Everyone is naturally prejudiced. We all healthily, properly, legitimately fear the unknown and unfamiliar (e.g. people who are different). In turn, and on the social front, we naturally, generally prefer "our own" or "our own kind/people" -- however unpleasant, disturbing, and hideously ugly this may sound today. And this is also true however "stereotyped," "bigoted," "racist," "undemocratic," "anti-equality," "anti-unity," and even Objectivist "collectivist" it may appear. As classical liberal Albert J. Nock noted a century ago: "Prejudice is the bedrock of individuality."
But none of this natural bias is ultimately or seriously antisocial, unfriendly, or unloving. Nor does it lead to "the breakdown of society," Hobbes' "war of all against all," civil war, internecine strife, or anything similar.
This is partially true because in true diversity (not the leftist junk) -- in a wide variety of inborn individual talents and developed idiosyncratic powers -- there is great strength. People tend to fruitfully and mutually beneficially interact in ways which generate great social loyalty, cohesion, and unity. They rather easily move toward social solidarity and The Brotherhood Of Man. This natural social cooperation -- not competition -- is also true because "variety is the spice of life." Life today would almost certainly be better and richer if we had, say, one more gender (maybe hermaphrodites) as well as, say, two more intelligent races (maybe Martians and Alpha Centaurians) to interact with.
Another reason why this natural bias doesn't lead to social disintegration and breakdown is because "opposites attract." In any given society, and especially a highly civilized one, there's a great deal of important information which people can, should, and easily, naturally do learn from "the other." There's tremendous benefit and profit in discovering, enjoying, and exploiting these considerable natural human differences.
Unfortunately, the post-1965 "Civil Rights" era conception of social tolerance is very much a disaster for the world. Even worse is the current post-1985 "Politically Correct" era of militant, hateful pseudo-tolerance a.k.a. "multiculturalism," "diversity," "inclusion," and "the politics of identity" as practiced by the viciously ignorant idealists who fervently worship at the High Church of Sensitivity. They attempt to brainwash and socially engineer all of us in the name of a fraudulent, impossible, and entirely undesirable "equality." Merciless social equalitarianism is about as false a god and ideal as you can get.
It's also worth noting here that the fundamental ideology of today's egalitarian, equalitarian crowd is entirely the tiresome and discredited one of 150-year-old socialism, altruism, and ooey-gooey, generalized communitarianism, communalism, and collectivism. Some call this "post-modernism." To achieve their warped version of social tolerance these activists, militants, and ideologues often end up condemning and even hating heroic, ingenious, saintly, "dead, white, European male" cultural authorities while embracing riff-raffish, ignorant, evil, "braindead, colored, third-world socialists."
To really promote social tolerance -- in the proper and best sense of the term --- one mostly just needs to know the truth. It isn't hard. To minimize illegitimate prejudice and intolerance of a physical kind -- of a criminal kind -- then a physical counter-attack by government is called for. To minimize bigotry and intolerance of a mental kind -- of an educational or propagandistic kind -- then a verbal or written counter-attack by noble individuals or voluntary social organizations is called for.
In other words, the antidote to illegal-type intolerance is special public coercion whereas the antidote to immoral-type intolerance is general private persuasion. It should certainly be noted that these two collective responses to social evil are very different and should never be mixed up or blended.
Perfect social harmony with regard to the ideal of "toleration" -- and with regard to everything else too -- is only achieved when all divergent groups and individuals compete and cooperate vigorously, energetically, and without limit -- but in a strictly non-physical, non-attacking way. This means a society of 100% persuasion, 0% coercion.
This last is also the only proper way to argue and debate the ideal path to truth, greatness, and universal human happiness -- or at least for the clear superiority of your nature and nurture! Complete freedom, economic capitalism, and social libertarianism generates this pure social harmony, perfect human interaction, and 100% achieved tolerance among both widely divergent human archetypes and fully realized individuals.
Today's coercive welfare-state laws use force to artificially attempt to create and sustain their false and evil version of social solidarity, unity, friendship, love, and tolerance. All such tyrannical laws are unnecessary, unworkable, and immoral. They are also utterly and without exception counterproductive, causing most of today's immense social disharmony and intolerance. For those who truly wish it, 100% truth about human differences and 100% liberty to exploit them is the only way to get to 100% social tolerance.