Okay, so a little bit of more info before i begin. this form is not about Mary Sues or OP Alicorns, but instead the point when a person is reading a story, where is the line when we roll our eyes because its so obvious that the author is just preaching their views to us. i believe we can safely exclude HIE stories and second person fics.
ALSO I DO NOT WANT TO START AN ARGUEMENT OVER IDEALS OR BELIEFS. ACT MATURE AND RESPECT OTHER'S OPINNIONS...even though they might be stupid...

Now, with the Self Inserts:
As you probably know, and please add on if I am missing or neglect somthing, is when we make a fictional character who is practically us in the flesh of this new world. This can vary from shape shift from humanity to Equine and being dropped in Equestria, or rather acting like we have always lived in this world. Some of theese are obvious, like a main or side character having the same name as the author, or they could be a clever new character that you intend to leave the audience none the wiser over.

many times, these characters are inserted into a world for the average fulfilment fics, and it is incredibly obvious that this character is just a medium for the author to send his messages and views to us. Like the supporter of the NLR who joins as a private and then becomes a general, constantly repeating the dasterdly deeds of Empress Celestia, and dies in a tragic death that inspires legions of troops, and causes Commander Luna/ Nightmare Moon to sob in sorrow. Or, more commonly the traveling Stallion who moves to ponyville and starts a relationship and later a family with one of the mane 6 or Background Ponies.

I can't say i've never done this, for ive made 2 self Inserts that I am not ashames of, "Knife Dancer" who is my crazy and immature side, constantly swearing, talking nonsense, and singing in public because he believes dignity is a waste of time, and kill off for the sake of fun(Also to show that the main character of my story is NOT a self insert, more on that later). While "Dancing Knives" has my tenacity, my immagination, freaks out over nothing, and even though is a weakiling, will not back down from a fight... which usually ends with him getting his ass whooped.
Anyway, they both are background characters and take up very little attention, and often are only used for the purpose of comic relief.

Now, on to the hard part, the main character OC's.
now, there are several types of main characters, be it the place holders, the side characters, main characters, "Alternate Cast" and etc, but I believe we can narrow down the personalities into 3 parts.
the "180", a person who has none or the opposite of our traits, often done to prove a point
the "Character" who may have a few of our traits, but for the most part their beliefs are made for the point of the story.
and 3, the thing i simply call "Us". Not a self insert, meaning that it is us in their shoes, but instead they carry a good portion of our beliefs.

Now, here are a few examples that i have made for future stories of mine or rather for the purpose of this thread.
180: If i write a satire or parody, I would make a bat pony character who is the personification of everything i despise about Luna's guards fics, from their mannerisms, allegiences, decisions, and intelligence, for he most part, his purpose is to be a joke.
Character: In my story Duty, the main character is named "Stargazer" and he is a well decorated soldier in the Equestrian Light Infantry. he is no Jingoist, and he has lost several of his ponies after several theatres of war agaisnt the enemies of Equestria. He comes home one day and overhears about how an orphanage is becoming too crowded, and their solution is to take the 18 year old Stallions and draft them into the military. He disagrees, and says that even though the military has been "good" to him, it was his choice, and he strongly disagrees about forcing young stallions into harm's way. Now, as with me, while I am not "Stargazer" (Knife dancer's purpose is to show that I am not him) he does express a few of my beliefs, about wartime policy and also about the draft, that no one should be forced to do anything. (this is just a very breif section of the story, not the entire thing).
WARNING! ECONOMIC POLICY AND POLITICS BELOW!
<Politics>
Us: In a future story Twilight's dad. (i don't know why, but i always think his name is Alan? so just bear with me for now.) is a economics teacher at a university. for the past 20 years Equestria and the rest of the world has been in a recession like no other experienced by the world. he is asked to speak at a conference, and he makes a few statements about how to fix the economy and what the policy makers are doing wrong, namely he says a few bad things about the two Princess' plan.
Eventually, when what he predicted was correct, he is hauled to their court, and he has to give advice on how to fix their problem, but as he explains, it is not that simple. So he goes off, fighting to gain support in the house of commoners, Nobles, and the favor of the Princess, and fix the economy. Pain stakingly working around personal agendas, outdated fiscal policy, good intentions, and bad economic policy. but eventually fixes the problem, and is placed as the head of the Equestrian Federal Reserve.

Now, while "Alan" might have my economic views (I am a macro economics minor) especially regarding things such as policy, he is not me in the person. he is a pre made character who i invented a personality to, but i am not him in the form of a pony.
</politics>

Now, to bring the 2 together. It is easy to have a main character OC, especially one who is close to the cast, be mistakes as a self insert. but where is the line, where do we see that this character is just a ranting author and it is so obvious that we drop the story all together or don't take them seriously? when does Big mac's homophobia over Applejack dating Rainbow Dash become so important that we can practically see the protest signs beside the author's computer? When does Fluttershy making excuses to avoid meeting with zecora so repetitive and obvious that the NAACP starts knocking on your door?
I'd love to hear what you think. I believe that we can all learn somthing from this when we write again, because while i feel that we NEED to put a bit of our soul into our OC's to make them believeable, i still stand by the fact that it is unacceptable to have an author make a self insert, claim that it is a character, but have no explainable reason as to why he immediatley goes "SCHWING!" over Luna on first sight for no other than "I like her mane" when we can all easily tell the truth is "She is best pony."

869159 Your HTML tags aren't XHTML compliant :P

I think it becomes too much when your character stops reacting based on thought at the moment. When you become tangential and completely off, but not in a way that is a important part of your OC or the plot. When you the OC meets two lezzies making out and yells at them, and then thinks about what he should do about it, and then rants about disgusting filth or something, then something about religion. (I'm not a hater and I honestly don't know what they think, or how they think.). Then it's probably a rant.

Well, I think there's a line when the self-inserted character has the author's name, and the self-insert character also has the same occupation and likes as the author. On the other hoof, OC is usually a much more... surprising and typically fleshed out person, sometimes so much so that the character surprises the real author with how much he/she has grown.

I think that there's a bit of the creator in everyone of their OC's, so it makes sense for a primary OC to share at least some of their beliefs. And if the belief their preaching is important to understanding the story, well, fine. I'm of the opinion that just because I don't agree with someone's opinion, it doesn't mean I can't enjoy the story. Like Dante's Inferno- I'm an athiest, and personally think the idea of Heaven and Hell is rediculous, but it's still one of my favorite books.

However, if the voicning of said opinion has no importance to the progression of the plot or the overall meaning of the story, THEN it starts to piss me off.

869273
yeah, i understand, when an author goes out of their way to do somthing or make a point and never mention it again, or have the rest of the characters go "You were right, we are wrong." Then yes, id say that is a self insert or mary sue being that "the story revolves around them".
Now, working of your lesbian example, if the two stopped, had a deus ex machina revelation on how "gays R bad" and then find men and live happily ever after. I agree with you, that is just politics and bad storytelling.

BUT, if it IS a part of a story, if the main character goes off and makes a complete asshole of himself (call them sinners, rejects, whatever). but later when he is all down on his luck and needs help, and THEY are the only two to help him, then it may work.

869335
I think that the character having a large roll and carrying the same name and traits of their author is a big red flag that they are a self insert, and following that, the creator would be very careful and defensive about them. of course, for a good one, we cant make accusations because we simply don't know much about the real person behind them. like i said, often self inserts are made for fulfilment fics, either dating or anti Celestia fics, where they are Luna's guards and trump thier regular counterparts.
I believe i break away from this mold because i straight up killed one of my self inserts, and used the other for brief comic relief durring an incredibly serious part of my story.

What I am trying to say is that it is OK to give your OC a few of your traits, it can help making them more believeable, but at the same time, don't make them TOO much like you.

My OC's have concrete personalities, I regard them as their own persons and have to wonder how they would act, whereas Dancing Knives is more what I would do.

869636 as I said, if the rant becomes tangential and hollow ( without a backstory to explain their behavior) it is a lecture. On the other hand a story of learning not to hate through charity could ALSO be a lecture if it became tangential and hollow. (Though I prefer them to well written ( as it can be) racist rant due to taste). The Iron Dream is a great example of a nontangential nonhollow racist story. (It is a book that would have been the book Hitler wrote had he been a scifi author) a story can have horrible message, but be a enjoyable read. If it is well written.

869760 the person who wrote the Iron Dream wasn't racist. He was making the point that evil twisted messages can be made palatable through words.

I think the lines we need to worry about aren't in the degree of self-insertion.

Do our OCs reflect our own beliefs about whatever they encounter? Always, even when the disagree with us. If I wrote a story about politics, and I wanted the main character to be an ardent anarchist, he wouldn't be a real anarchist. He would be some sort of weird parody-anarchist, because I am not an anarchist. If your OC is unlike you, they are like someone else from your point of view. This doesn't mean they're bad characters, uninteresting or poorly written, but they are written from the author's point of view + the author's imagination.

Are all self-inset characters bad? NO. James Bond was a self-insert (and probably wish fulfillment) for Ian Flemming. (who was a British spy after WWII and has some Scottish ancestors, but probably didn't have a laser watch) The books and movies are still fun. (Though I use Bond a lot a a character who has all the symptoms of bad writing but is still fun)

Can you give a character your name and still write a good story? I've seen it done, but I would bet against any such story being well-written.

Second point: On author rants:

If I wanted to be preached at, I'd go to church.

I, the reader, should only know enough about the character's beliefs to understand their actions in the story. If gays aren't a key part of the story, I should have no clue how the main character, or any character, feels about gays. Or the Mysterious Mare-Do-Well. (that actually happened in a story I read; whole ten to a dozen paragraph on how hat was an awful episode, in the middle of a Romance fic. I agree, get on with the plot.)

It all comes down to interesting characters and plot-relevant details about them, I guess.