One in four children are bullied because of their faith, a study has found, as the Tories criticised local authorities for not expelling more bad pupils.
A lack of cohesion between faiths was to blame, said the survey by the Beatbullying charity.
According to the study, those bullied because of their religious beliefs often began to question their faith, stopped talking about it, or even felt ashamed of it.
And bullying led many young people to self-harm, drink alcohol or take drugs as a consequence, the charity claimed.
The results showed that one in five young people choose to mix mostly with friends of the same religion, while one in 20 said that their families do not approve of them having friends of other religious faiths.
Six out of 10 young people have an understanding of their peers' religions and more than half (55.9%) have friends from and mix with young people of all religions.
Nearly three-quarters (71.1%) said they could choose their own friends irrespective of religion and 56.3% of families allow their children to have a mixture of friendships.
But of the 47% who practice their religion, 23% reported being bullied because of their religion or faith.
The most common forms of bullying are verbal (19.9%), psychological or emotional (17.3%) and physical (11.3%).
Cyber-bullying was experienced in 6% of cases and 9% have been bullied because of the religious symbols they wear or present.
The research, published today to mark the start of Anti-Bullying Week, found evidence of segregation and religious intolerance among young people.
While more than twice as many young people as adults practise a religion, almost half of young people (48%) never talk about religious issues at all.
Emma-Jane Cross, Beatbullying's chief executive, said: "Beatbullying worries that this lack of cohesion is cultivating at best a lack of understanding and at worst a lack of tolerance of other faiths.
"Beatbullying's work proves that by providing outlets for young people to discuss the issues that matter to them, we can effectively reduce anti-social and violent behaviours between young people."
The Tories today criticised local authorities for not expelling more school bullies.
Nearly half of children said they had been bullied in the last year but only 80 children were expelled from school for bullying, government figures show.
In more than two-thirds of local authorities no children were expelled for bullying.
Across England, 6,800 children were suspended for bullying, 5,710 of which were from secondary schools. But 98.5% of serious punishments for bullying – expulsion or suspension – led to the offending child being returned to the same school.
The Tories accused the government of making it harder for schools to expel children permanently.
The shadow schools secretary, Michael Gove, said: "It's unbelievable that with the widespread concern about bullying just a handful of children are receiving the ultimate sanction against them.
"The victims of bullying shouldn't have to put up with seeing their tormentors stroll back into the classroom after a few days away from school."
The Tories would scrap independent appeals panels that mean children expelled from school can overrule the decision of the headteacher, he said.
"And we would give teachers more powers to ensure a safe and secure environment for children," he added.
"Our reforms would give schools the power to take a 'zero tolerance' approach towards serious offences such as bullying and give teachers the tools they need to maintain discipline in the classroom before it spirals out of control."
A survey of children by the government's school inspector, Ofsted, found last month that 44% of children had been bullied in the last year.