Some people judge, some people judge less. Everyone does it to some degree, and the reason why we judge in the first place is probably due to some evolutionary impetus. But as with many of our human traits that made sense before technology and civilization, the question is, are they still relevant?
Earlier in the thread, someone else said something to the effect of your actions are all that matter. I think your actions, in combination with what you say, define your character. And a group of characters together define a culture. I agree with others than modern communication technology (particularly the Internet) has gone a long way to break down cultural barriers. A few generations ago, cultures I think were more rigidly defined, geographically, racially, politically, etc. Increasingly those things get blurred.
I'm looking at this question from the perspective of a judge, i.e. an employee of the legal system, the head of a courtroom. What does this person do? He judges whether or not a law has been broken, or at the higher levels, is the law even valid. But what are laws? At least in democratic-type societies like the USA, the laws are just encoded versions of social norms, the way most people want things to be. Every looked at some of those obsolete or ridiculous laws from 100 years ago? The reason they are obsolete or ridiculous is because they represented a very different culture. You don't even have to get into the "hard" philosophical/ethical/political stuff: take laws about horse-and-buggies. I'm just making assumptions here, but I'll bet there's at least a few counties that have laws on the books, and they presumably made plenty of sense at the time... but now they're just plain irrelevant since we no longer live in a horse-and-buggy culture.
As far as getting uncomfortable drawing the line as far as what's OK to judge and what's not... perhaps it has to do with how personal something is, and how it can be objectively it can be discussed. Abortion's a great example. I'll use my friend's mom as an example. She's hard-core anti-abortion, and certainly judges anyone getting abortions. And to her, it is an objective decision, because that's what her religion says; to her, religion is more fundamental than gravity or 1+1=2.
Compare that to an agnostic position, that says, we can't (yet) know if a soul really exists, and we don't have objective criteria for defining when a fertilized egg becomes "human" rather than a glob of cells, and given this, abortion is highly personal. Even if life begins immediately at conception and there is a soul, what if there's no question that the child will be born into a miserable life (extreme poverty, abuse, hunger, drugs, slavery, etc)? But what if the child rose above all that and came up with a cure for cancer? But what if it was found much later that that cure had some unforeseen consequence that was even worse than cancer?
Perhaps a less incendiary topic: do you judge fat people? I'll admit, I have a "gut" (get it?) reaction when I see an obese person, but then I think, what if this person has a glandular problem, or some congenital issue? Sure, a lot of fatties are of the lazy/over-eating type. But there are those who can't help it, despite doing all the right things.
I think people are hesitant to draw the line because it forces them to answer questions they don't want to ask themselves. And/or, they know that the topic itself is a big can of worms, and they simply don't want to go there.
Let me give another example: diet. Can of worms alert! You've got the USDA saying one thing, Dr Oz saying another, Gary Taubes with his opinion... As far as I can tell, the current "state of the art" can't answer the question, what is the optimal human diet? Even if you don't agree with Gary Taubes's conclusions, I think you have to agree about one of his points, and that is it's virtually impossible to conduct a "perfect" scientific study of human nutrition. You simply can't change just one facet of human diet; conclusions drawn from experiments where two or more variables are changed are always imprecise.
Being a technology guy, this analogy seems apt: say I have a computer that doesn't seem to work correctly. At the most basic level, it's fairly easy to troubleshoot: is it plugged it? Do the major components work if swapped in/out of another system? Say we go through all levels of tech support, and just can't pinpoint the problem. What if, one transistor (of more than a billion in a modern CPU) was of marginal tolerance, enough that it just barely passed quality control, and it just so happens that the "synergy" of the particular problematic system causes it to fall out of tolerance, such that it otherwise works fine in 99% of other systems out there? How many people out there are capable of drilling down to that level to figure out what's really wrong? But the CPU is a human invention, so there's somebody out there who knows.
But life on our planet is like this ultra-complex system that wasn't invented by humans, and nobody understands how it all works. With every breakthrough in understanding, there's a boatload of new questions to be answered. Some things are seemingly easier to study and understand, and some are harder, maybe completely intractable. Take Newtonian physics versus the ethics of abortion. Or even less dramatic, calculus versus human diet and nutrition.
If I don't have a position on something, I don't think it means I'm intellectually lazy or ignorant or unintelligent. Maybe it's a cop-out answer, but I think some things simply aren't knowable at this point, so how can I be anything but agnostic? And if I'm agnostic, how can I judge? Of course, I have my prejudices and biases like everyone else, and those lead to snap judgments. But I make an honest effort to recognize the preconceptions in myself, and avoid letting them drive my actual behavior. But, take any one (of literally countless) topic of human study, and you'll find people who have dedicated their lives to learning everything they can about it. And while they may be brilliant and make tremendous progress (e.g. Newton, Einstein), they still leave the field with just as many new questions as old questions they answered. Is there any field of study where it's case closed, we know everything there is to know? I don't think so.
So if you're not agnostic on a topic, I guess that gives you the "right" to judge. But how is it that your knowledge is so perfect and complete that you're not agnostic? Surely everyone here has seen a classic Internet flamewar on human diet and nutrition. "Dr Oz says this." "Yeah, but Gary Taubes says that." "Gary Taubes ignored study XYZ in his work." "Study XYZ was flawed." "Study ABC has been peer-reviewed a million times and says they're both wrong." And it goes on and on. Certainly nobody in the debate has perfect and complete knowledge on the topic---yet they argue it so passionately. Is arguing not another form of judging? An argument is basically saying, "I judge you to be wrong."
Certainly, you can judge in the face of ignorance, logical fallacies or simple misunderstandings. And for those things it's easy to draw a line. But when you get into the "heavy" stuff, everyone's knowledge is imperfect and incomplete, therefore it's impossible to draw a line in the sand. So, you make the best with what you have; you use the knowledge and intelligence you do have to draw a line---but not the line, as the next guy has different knowledge/experience/understanding/intelligence, so he draws a different line. The line you draw is part of your character, and groups of people with similar lines form a culture.
How passionate are you about your line? Maybe you're agnostic, and simply unwilling to even draw a line. Maybe you can't live with ambiguity, so you're compelled to draw a line, any line. And maybe that line is drawn from something so fundamental to you (such as religion) that you defend it fiercely, and segregate yourself from others with a different (or no) line.
Sorry, got rambling there.
This discussion made me think of Harper Lee's To Kill a Mockingbird... it had me off looking up Atticus Finch quotes.