Religious Education in Wiltshire - no Bibles allowed.
Mr Simpkins, who said Tristian had been suffering for around two years, met his son's teacher on Monday. He said after the meeting: "I think they really want me to withdraw Tristan because it's the easiest option for them.
"He would go there and disagree with what the teacher said and they probably don't want that in the class.
"He's decided to stay put because if he comes out of the syllabus he won't be able to sit the religious education GCSE. He'll study Islam to a certain point.''
Mr Simpkins said his son's lecturer once called him at home after Tristian read the Bible during a lesson. He said last Tuesday Tristian was ejected from the room when he wrote God Save The Queen on his exercise book.
"We've been having problems for some time," he said. "The whole Year 10 syllabus is Islam, Muhammad and very much one-sided. There are no Bibles in his RE lessons. They give out one book, you can't research it yourself, which I think is wrong and a lot of his class mates feel the same way. The children don't like it."