West Wing: What was that about a 'shibboleth'?

[mundania]

Did anyone watch West Wing last night?

The President (Martin Sheen) was meeting with a Chinese
refugee to test if he was a 'true' Christian as opposed
to a 'coached' one. According to the President, could
tell if he was a true or fake one by the term shibboleth.

However, I don't understand how that would determine
the authenticity of the Christian. Can anyone shed some
light?

 

[BDawg]

Obviously, no words or phrases can prove someone is a Christian. Any kind of speech can be coached.

The question Bartlett was going to ask was more obscure, and he hoped a coached individual wouldn't have learned.

Of course, the guy beat him to the punch.