I recently got back into Irvine after a trip up through a large swath of NorCal to visit friends and family. I really have two sets of family up there; one is my "older brother" (met many moons ago through the Big Brother/Little Brother program) with his family in the Bay Area and the other is the group of actual genetic family in the Sacramento area.
I've mentioned being an Atheist and being a member of Atheists, Agnostics, and Rationalists at UC Irvine to my brother and his family, but I still haven't to my family in Sacramento. Most of my hesitation to "come out" with that side of the family is the fact that they're all deeply christian and (actually not good) lean towards an ID view of the world which actually bothers me more than the theist/atheist divide.
I had promised to myself that I'd try and bring up the topic while I was up there for this visit, but didn't end up going through with it. Started to sound out my cousin while he was firing up the grill in back, but ran into the ID/Evolution wall and decided to cut my losses there.
I really don't think my family would go ape-shit and cut ties if they officially found out as I think most already know to some extent, but....I'm just not sure. In my head there's a less than 1% chance of it being really bad, but I don't really want to risk it.
The truth is that for the most part my family lives up the good ideals of Christianity that we (Atheists) tend to forget actually exist. For all the blowhard Ted Haggard assholes there are going to be 10 people like my family who really believe and that belief is a cornerstone of their philosophy, but also don't really go out of their way to impede progress for the rest of humanity. For the most part they just want to live their lives, worship as they see fit, and move on.
So this lead me to the thought (mostly self-justification) that "coming out" them isn't worth the less than 1% chance of a bad reaction. I enjoy spending time with them and 90% of the time that I spend up there is doing the same old family shit that most American families do. BBQing, watching movies, and just shooting the shit about the everyday events in life. It's like a sanctuary for me from the rest of the world and I'm not sure how much risk to that I'm willing to go in to for a topic that I know isn't going to get anywhere on either side.