Mufti Shah Sadruddin, a senior Muslim scholar, made the comments in 2013 and they have now been uncovered by a new ITV documentary.
The documentary shows Mr Sadruddin, a leading religious figure in the Jamaat-e-Ulama UK, or Council of Muslim Scholars in the UK, and in the British Bangladeshi community, criticising atheists who he said had insulted Islam, in particular a Bangladeshi blogger.
Mr Sadruddin, who now runs the Al-Ashraaf Secondary School in Ilford, said: “He said: “He is a bastard, a traitor and a shameless person. Child of a hypocrite, he swore at my Prophet.
“This son of a bastard is challenging us!
Mufti Shah Sadruddi said made the comments at a rally in 2013
No son of a bastard will remain alive after swearing at my Prophet
“O’ Bangla’s scholars, O’ Bangla’s Muslims, wake up. No son of a bastard will remain alive after swearing at my Prophet!”
The comments were made at a rally held in the wake of the death of another Bangladeshi blogger Ahmed Rajib Haider, who made jokes about Islamic beliefs and took part in protests calling for the execution of convicted Islamist war criminals.
At similar rallies in Bangladesh at the time, Islamists were using the term ‘atheist’ to attack the secular government and the protesters.
Mufti Shah Sadruddin, a senior Muslim scholar, made the comments in 2013
Mr Sadruddin said in the 2013 “No son of a bastard will remain alive after swearing at my Prophet”
Mr Sadruddin, the rector of a secondary school, ran for election as a Conservative councillor, portraying himself as liberal, tolerant and opposed to hatred.
He failed to win his seat in Newham in 2014’s local elections.
In a video filmed in the run-up to the Newham election, he said: “I believe in equality, in fairness, I believe in loving the human race and I hate to hate anybody.”
When approached by Exposuree: Islam’s Non-Believers, which airs on ITV tonight at 10.40pm, Mr Sadruddin said that his speeches did not incite hatred, there was no intention to promote violence and he had specifically said “our jihad will be non-violent”.
Mr Sadruddin was speaking at a rally after the death of Bangladeshi blogger Ahmed Rajib Haider
The Conservatives were approached for a response but did not comment.
Exposure: Islam’s Non-Believers investigates the lives of ex-Muslims, who face extreme discrimination, ostracism, psychological abuse and violence as a result of leaving Islam.
Some are at risk of suicide, or self-harm, or have been physically and psychologically abused by their closest family members. Most are terrified of being shunned by their own family and friends if their true beliefs become known.
Some of those who speak in the programme have asked to remain anonymous for fear of reprisals.
Mufti Shah Sadruddin ran as a Conservative council candidate in 2014
The film follows the Council of Ex-Muslims of Britain, a volunteer support groupwhich supports ex-Muslims, often referred to as apostates or unbelievers, both in the UK and abroad.
Dr Omer El-Hamdoon from the Muslim Association of Britain says people can leave the religion of their own free will and should not be punished.
But he says it is not surprising that those who do leave are shunned.
He said: “The Muslim community is a community based on religion, so if a person chooses to stop being a Muslim they can’t really expect that the Muslim community is still going to say to them, ‘You are still part of our community.’”
The programme also reports on how the danger for ex-Muslims who live in Islamic countries can be even higher.
Apostasy carries the death penalty in a dozen Islamic countries.
It is not illegal for Christians to drink alcohol in Iran but under Islamic law, Muslims are forbidden from drinking and it is illegal for Muslims to convert.
Many people faint after eight strokes due to the severe pain of the corporal punishment.
Yasser Mossayebzadeh, Saheb Fadaie and Mohammad Reza Omidi are due in court later this month.
Atheists face a double threat – persecution by their own government, and the risk of murder at the hands of Islamist gangs.
Arif Rahman, a Bangladeshi blogger now in hiding in London, says he sees bloggers as a resistance movement against religious extremism.
He said: “When we started writing in 2006, we did not think the people would be killed over this. And in 2013 our first colleague Ahmed Rajab Haidar, he was an architect, was hacked to death in front of his house. That was the first time we realised this was real this could potentially happen.”
Exposure: Islam’s Non-Believers is on ITV at 10.40pm this evening.