The teacher at the centre of protest for teaching LGBT relationship lessons has received threats and other "nasty" messages.
Andrew Moffat, of Parkfield Community School in Birmingham, was told "You won't last long", Sky News reported.
The assistant headteacher's No Outsiders programme has sparked protests by mainly Muslim parents who object to their children learning about same-sex relationships.
Mr Moffat told Sky News: "I have had some very nasty messages and letters. I had a message to say 'You won't last long'.
"So there has been some very difficult messages to receive."
The No Outsiders programme teaches according to the Equality Act, and Mr Moffat said you cannot pick and choose which parts of it to apply.
Pupils are taught about the positive values of diversity, tolerance and acceptance, in a broad curriculum encompassing LGBT rights, same-sex relationships, gender identity, race and religion.
Last month Mr Moffat revealed that the daily demonstrations outside the school gates had left some children in tears.
As a result of the disruption and negative effect on the youngsters, the school decided to suspend its No Outsiders programme until an agreement could be reached with concerned parents.
The PSHE teacher said the lessons do not make reference to sexual acts, and pupils are simply read stories where people have different families.
He said: "In Britain today, schools have got to find a way to tackle that rise in hate.
"We can't ignore this. We have got to find ways to teach children that if someone has got a headscarf on, I am not frightened of them.
"If someone has got brown skin and I have got white skin, I am not frightened of them. I can be friends with that person."