Because its not a source of embarrassment. What's a worse thing to ask when the subject comes up? Are they even remotely similar in distaste?
1. Hey, is that a fashion statement or an actual belief in God? I only ask because I noticed that crucifix around your neck.
2. Hey, do you have genital herpes? I only ask because I see some cold sores around your mouth?
I would never ask anyone either of those questions. They are quite similar in distaste, in my opinion.
Also, it is very difficult for me to have a conversation with someone adamant in discussing their silly (in my view) beliefs (as many biblical literalists are)--we have no common ground. This would hold equally true for both Scientologists and biblical literalists (just so you know I'm not singling out a particular silly belief).
Cheers
Edited by Michael, : edited for clarity