Which one teaching really hurt you when you found out that it was not true?
My number one thing is finding out that the name "Jehovah" was NOT in the bible like it was in the New World Translation (tm).
Christians did not call God "jehover" "jehovah" or by his first name, no more than you would call your father by his first name when you were a child. (I would have peeled my cheek off the wall from the slap if I tried that bit of disrespect).
The mis-quoted historians, the out of context historian teachings, just utter garbage. It hurt me because I felt that I had a "special" relationship with god, yet I acted as a scribe and pharisee towards fellow mankind.
Which teaching really hurt you when you found out that it was a lie?