A court in Saudi Arabia has been criticised for sentencing a teacher to over three years in prison and 750 lashes for mocking Islam.
Public practice of a religion other than Islam is banned
Human Rights Watch says the Saudi judiciary is imprisoning people who advocate genuine educational reform.
Mohammed al-Harbi was found guilty of promoting "dubious ideologies" and preventing students from going to wash for prayer.
He says he is the victim of a campaign organised by religious conservatives.
Mr Harbi was taken to court by a group of teachers and students at his school in al-Qassim Province, north of Riyadh.
Mr Harbi says they were angered by his criticism of militants who have carried out a series of attacks in the kingdom over the last two and a half years.
Mr Harbi discussed Christianity, Judaism and the dangers of terrorism with students, and posted signs against terrorism around his school, Human Rights Watch says.
He also reportedly encouraged his students to analyse differences between the Koran and the Sunna, a body of traditional sayings and customs attributed to the prophet Muhammad.
Sentencing Mr Harbi to 750 lashes and 40 months in prison on Saturday, Judge Abdullah Dakhil accused him of "trying to sow doubt in a student's creed".
Human Rights Watch condemned the courts decision for restricting freedom of expression.
"Despite recent education reforms, the Saudi government is imprisoning schoolteachers for having open discussions with their students," said Sarah Leah Whitson, its Middle East director.
"As long as schoolteachers face persecution for doing their job, Saudi children will lose out."
The BBC's Middle East analyst, Roger Hardy, says tensions between liberals and religious conservatives are a constant feature of Saudi life.
But liberals feel that, at a time when the authorities are anxious to show the world they oppose religious extremism and al-Qaeda-style violence, they should be supporting people like Mr Harbi, not sending them to jail, our correspondent says.