If you lived in a society that killed/tortured atheists for not believing, it would be extremely rational to (assuming that you value your life over your advertised beliefs), at the very least, pretend that you believe in whatever bullshit people want you to believe.
True. To the outside world it is equivalent though.
Furthermore - there's a saying that "believe in it long enough - and you'll think it's true". So you have to be careful with that - sometimes appearances become deceiving (what you show becomes what you are).
