One in 10 young British Asians believes so-called honour killings can be justified, according to a poll for the BBC's Asian Network.
Samaira Nazir was murdered by her relatives
Of 500 Hindus, Sikhs, Christians and Muslims questioned, a 10th said they would condone the murder of someone who disrespected their family's honour.
Figures show 13 people die every year in honour killings, but police and support groups believe it is many more.
Religious leaders said they would hold a national conference on the issue.
Honour killing is a brutal reaction within a family - predominantly Asian and Middle Eastern - to someone perceived to have brought "shame" upon relatives.
What constitutes dishonour can range from wearing clothes thought unsuitable or choosing a career which the family disapprove of, to marrying outside of the wider community.
The Metropolitan Police are investigating 200 deaths linked to honour killings.
Kidnaps, beatings and rapes have also been committed in the name of "honour".
Liza Booth, from Asian Network, said clerics from all the faiths would hold the gathering later in the year to discuss how to make honour killings a thing of the past.
The 16 to 34-year-old age group interviewed in the survey needed to be persuaded such killings were not acceptable, they said.
One interviewee told the radio station: "A lot of people treat their family as everything they have got. So if someone hurts their family the law might do nothing about it, you might have to deal with it."
Navid Akhtar, a journalist who has been examining the issue, said honour was ingrained into Asian society.
"Most of the Asians who are in Britain today come from very tribal communities.
"Honour is a big deal, it's kind of caught up with your property, it's caught up with your women and if anybody comes close to threatening you, you have to avenge your honour."
Dr Aisha Gill, a lecturer in criminology at Roehampton University, told BBC Five Live that convincing the Asian community that honour killings were not acceptable was the right approach.
"I think it's absolutely essential that there is a collective responsibility, and this is not just for agencies, but for communities that are affected by it.
"[The government should] send out a clear message, an unambiguous message that such violence against women will not be tolerated."
In one recent case, two men were jailed for life for murdering their relative after she fell in love with an asylum seeker.
Greengrocer Azhar Nazir, 30, and his cousin Imran Mohammed, 17, stabbed Nazir's sister Samaira 18 times at the family home in Southall in April 2005.
The 25-year-old recruitment consultant was killed after she asked to marry an Afghan man - instead of marrying someone in the Pakistani family circle.