and I don't do bad things to people, by the way
Everyone is the hero of their own story, even the villains.
Is that what I got the negative karma for?
Like shminux said, don't sweat karma. It's not a big deal. I cared way too much about karma when I first joined, because this was the first time I'd found an internet community whose opinions I genuinely respected. I still care too much about it, but not nearly as much as I did. I think you got the negative karma primarily because of tone - as several people mentioned, and you've acknowledged, you came across as "a dark lord on the mission to bind people to his will and be like you". My impression is that you have a tendency to write this way. Which isn't a terrible thing, you should just be aware of it. People rarely understand you exactly as you mean them to. Secondarily, I think you got it because changing other people's mind isn't really an exercise in rationality, as rationality is fairly rarely convincing to people. Lastly, it may be to poor editing "he has devoted his life to already invested a lot of it in religion", and "I haven't been able to change nobody's mind". I make mistakes like this all the time, when I go back and change part of a sentence and forget to change the other. (For the record, if anyone notices mistakes like this in my writing, please point them out to me, because I'm morbidly embarrassed when look at my recent comments and I have a three day old comment with improper subject verb agreement) But it makes your (or my) post look like it's unpolished and you didn't put any effort into it. Alternatively, if English is not your native language, as is the case for many users, you may want to put a disclaimer at the beginning of your posts. The welcome thread also has information on people who can give you English help.
Is it that the majority of LessWrong thinks that it's bad to change someone's mind even when it's only for his own good?
Well the way you phrase it, no. But there are several reasons I wouldn't try to change someones mind in some of the examples you've mentioned. Your programmer friend at Uni is probably too devout to be swayed. Spending what would be about one ninth of his waking day praying does seem like a waste, you're right. But I don't think many people who do this could be convinced of atheism regardless. I did find the situation about your "brother" (who I guess isn't your brother?) compelling, but it would probably be better suited to an open thread. FWIW, my advice is to A. do nice things for him, as moridinamael suggested and B. After doing A. for a little while, address it head on, if it does not work, ask him what you could do to improve your relationship. Express that you enjoy his friendship but have gotten the impression that he thinks XYZ of you. B. may or may not be appropriate given the level of friendship between the two of you, but since you used "brother", I'm assuming you're fairly close and that such a conversation wouldn't be too terribly awkward.
Pick one (or several) of the following. I used specific examples, therefore anything similar still counts.
1. You have a friendly new acquaintance who is pretty much an average person. He is a theist and doesn't believe Evolution, you have already had a polite debate about that. Convince him to believe in the truth*.
2. One of your friends is very deeply religious - he has devoted his life to already invested a lot of it in religion. Unexpectedly, he is also highly rational (as a personality) and very intelligent, he studies a technical degree (enjoys it), he has read books about critical thinking (he even knows a little about biases) and he says that he will stop believing in religion if you disprove it. Debating with him so far didn't help (also he isn't too good - he isn't aware of expected value and such ideas). For his own good, convince him to change his mind in the direction of the truth. He is wasting a huge potential and that's not only bad for him, but also for humanity. Also, he will feel more comfortable in his new, more sensible beliefs.
3. Your brother dislikes you because of his impression of you that was created several years ago and wasn't updated to reflect the changes in your personality. You easily make impressions to other people that are vastly different from his impression of you. Change his impression, so that he sees you truthfully.
[I have removed 4., because it wasn't about changing the mind of someone who isn't a rationalist, but about coming up with a good psychological mechanism - it deserves an entirely new thread; I suspect that 3 might be too different from 1 and 2, but it's too late to make a so big change to the thread]
I know at least one person for each category. And I haven't been able to change nobody's mind. Have you succeeded in a similar situation? Regardless of whether you have, what strategies do you think would be winning in the 4 situations? If some of them sounds good, I might even try them out and share the results. I'm especially curious about how to approach in #3, because if there is a way, it would come from low-level psychology, which is something I adore.
So, the aim of this thread is for the participants to try and change someone's mind and then tell the story.
(also, I'm willing to accept ideas of other templates for classical situations similar to those, in fact I think I had one or two more ideas, but I can't seem to recall them)
*Needless to say, if at any point, anyone proves to you that his direction is in fact the truth, it would be better to change yourself in that direction instead, but that's outside of the scope of the thread.