Hello!

Looking at the sentence itself, I don't believe 'tortuous' stands firm on its own-it needs to be qualified by something (tortuous how?), as alone it implies that being an atheist in America is the same as being an atheist in another country--which isn't quite what they're saying. 

You're also right that "social costs" doesn't match the person's speech, however, as it's an ambiguous term that doesn't clarify what aspect of society is taking its toll. 

I think the best approach would be to make a better transition leading into the example of speaking with African-American women: "The consequences for being an atheist here are also somewhat tortuous in terms of being accepted by your peers". Here's a few other options along that vein:
"...tortuous in terms of
-social interactions
-wanting others to understand your point of view
-communicating with others

The idea is to help the dialogue transition into the example of the next paragraph. Hope this helps! =)