Christians, Yazidis and other minorities are victims of a genocide by ISIS according to MPs from all parties in a unanimous vote on Wednesday.
The House of Commons passed a motion by 278-0 which recognised genocide has been committed and called on the government to refer the matter to the United Nations Security Council (UNSC).
However the government refused to support the motion and ordered all Tory MPs who are on the payroll to abstain. This meant 40 per cent of Conservative MPs were barred from voting.
Foreign office minister Tobias Ellwood said in response that he believed acts of "genocide had taken place" but added the term had a "legal definition and the government is not the judiciary". He repeated the Prime Minister's argument that genocide is a matter for international courts and not governments.
However the Christian MP Fiona Bruce who tabled the motion called this a "circular argument" because the International Criminal Court (ICC) cannot intervene until it is instructed to do by the UNSC, of which the UK is a permanent member.
In retaliation Ellwood said the last time the UNSC had made a referral to the ICC was in 2014 and it had been voted by Russia, another permanent member.
After the debate Bruce told Christian Today the example in 2014 was on a "completely different issue".
She said: "It was not about the genocide of Daesh [ISIS] which in my view no country would condone.
"I believe the referral should be made without comparison to 2014 and am confident it will not be vetoed."
David Burrowes, trustee of the Conservative Christian Fellowship (CCF), agreed and said the decision was "about the principle".
He told Christian Today after the debate: "Just because there is a prospect of a veto it does not mean you do nothing. Just because it may be challenged, it can't mean you do nothing.
"Once the threshold of genocide has been reached, as it clearly has, we have an obligation."
He added the "overwhelming vote... sends a very clear unanimous voice of the House of Commons that the government needs to take action.
"This issue will not go away. The payroll was ordered to abstain from the vote and no doubt many of them would have supported the motion as well."
Labour's faith envoy Stephen Timms also spoke to Christian Today in the aftermath of the debate, which he described as "powerful".
The MP for East Ham acknowledged Ellwood "did use the word genocide which is a step further than any other government minister has gone so far".
He said the government was "changing what it is saying" but added: "I am not sure what sort of response it will be and I don't know how full it will be.
"I am concerned it won't be as full as the Commons expected."