This is a PR issue, and it would probably be nice to have a FAQ explaining what are and what aren't our beliefs.

Or in other words, some sort of LWean Creed? :)

But yes, you're right: having some clearly defined core beliefs is indeed useful for delineating in-group/out-group and avoiding the non-central fallacy where things like that guy and his STDs and walking on broken glass are clearly not normative or common or related to the LW memeplex and represent his glib rationalizations. Yvain wrote a little bit about that recently: http://slatestarcodex.com/2014/07/14/ecclesiology-for-atheists/

Personally, I prefer using the LW survey for this. It doesn't address many of the higher-level issues but at least for basic object-level stuff like cryonics, it's useful for laying out clearly what LWers tend to believe at what level of confidence.

(And to point out something yet again, this is why not being allowed to add the basilisk question to the LW survey has been so harmful: it lets a very niche marginal belief be presented by outsiders like Stross as a central belief - it's suppressed by the Grand Leader as a secret, it must be important! - and we are unable to produce concrete data pointing out 'only 1% of LWers take the basilisk at all seriously' etc.)