The Archbishop of Canterbury has criticised the "suppression" of Christian unions in universities.
Dr Rowan Williams defends the freedom of speech
Dr Rowan Williams said the refusal by some student unions to recognise evangelical Christian groups looked like a "fear of open argument".
Writing in the Times Higher Education Supplement, Dr Williams said it was not a crime to hold traditional views.
But the National Union of Students said all local unions were trying to do was curb Christian societies' exlusivity.
Concerns arose when the student guild at Exeter University suspended the Christian union (CU) from its group.
The guild said that, by asking members must sign a form saying they follow Christ, the CU breached equal opportunities and was not open to all.
Members of the Christian union have threatened to take legal action against the guild.
And at University of Birmingham, the CU said the student guild wanted it to change its constitution and impose a guild leader onto its executive.
The CU said it has also had its bank accounts frozen by Guild authorities.
'Expression of hate'
In his article, It is not a crime to hold traditional values, Dr Williams said: "The danger in issuing sanctions against a body whose views you disapprove of is that it looks like a fear of open argument.
"If disagreement is to be silenced because offence may be caused, that is not good for intellectual life; it personalises and 'psychologises' all conflict of ideas and denies the possibility of appropriate detachment in debating issues."
Dr Williams said, while the views of evangelicals on the issue of homosexual sex may be "embarrassing" to liberal Christians, traditional values should not be compared to holocaust denial or racial bigotry.
"Quite often in discussion of Christian attitudes to homosexuality (and this is often the presenting issue where Christian unions are concerned), it is taken for granted that any statement that a form of behaviour might be sinful is on a par with the expression of hate."
This means, he said, it is "impossible for a conservative Christian, Catholic or Protestant or, for that matter, an orthodox Muslim to state the traditional position of their faith without being accused of something akin to holocaust denial or racial bigotry".
He added: "To challenge behaviour may be deeply unwelcome and offensive in a personal sense, but it is not a matter for legislative action."
Dr Williams also challenged evangelical groups to look carefully at the expression of some of their beliefs.
"No doubt some Christian unions might do well to undertake a little hard self-examination about whether their language is vulnerable to proper challenge.
He added: "They may need to affirm more clearly and credibly the distinction between declaring behaviour unacceptable and in effect passing judgment on a whole category of persons."
The president of the National Union of Students, Gemma Tumelty, said the union agreed that silencing disagreement was bad for intellectual life.
"But Dr Williams not consider that unfortunately some Christian unions themselves proscribe opinion through limiting access to others and that this is what students' unions are trying to mitigate.
"Students' unions are not seeking to be 'arbiters of acceptable opinion' as he claims.
"They are seeking to allow free flow of opinion within societies as well as between societies," she said.
The student movement had a proud record of supporting faith groups, interfaith dialogue and ensuring the happy existence of equal opportunities structures, she added.