I have a similar problem with the musical community -- I know from experience that no group of musicians who invites me to play with them will think any less of me as a person or shame me in any way for having less talent or skill than they do, and yet I find it extremely difficult to alieve that I will fit in with a group of musicians at a jam session.

I used to be on the other end of this self-directed discomfort in the Jewish community -- I heard over and over again about how laypeople and recent converts were too terrified and ashamed of their low skill levels or low cultural fluency to attend even relatively passive events such as festive meals. I am not aware that anyone has developed any Jewish programming that successfully addresses this issue...no matter how welcoming, inclusive, or beginner-friendly an event is, there is still a very large share of the target market that will say that they didn't go because it was too foreign and threatening.

I had somewhat more success attracting newbies to Less Wrong San Francisco meetups, although, even there, despite my best efforts, for each person who came and said they were a newbie, about one person said they were a newbie and used that as a reason not to come.

Is this a general social problem with a general solution? What, if anything, can an in-group do that will reliably prevent prospective members from feeling insecure and marginalized?